Sodium hydroxide


Dichloroethane (ethylene dichloride) – Uses of Dichlorethane :

– manufacture of ethylenediamine, ethylene glycol, polyvinyl chloride, nylon, rayon, various plastics
– solvent for fats, oils, waxes, resins, rubber, and for the extraction of spices
– fumigation of grains (cereals), orchards, …
– manufacture of paints, varnishes, cleaning, soap, cleaners, …

Posted in: FAQ - Dichloroethane (ethylene dichloride)

Dichloroethane (ethylene dichloride) – Manufacturing process for Dichlorethane :

1,2-dichloroethane,commonly known by its old name of ethylene dichloride (EDC), is
mainly used to produce vinyl chloride monomer (VCM) the major precursor for PVC production

EDC is made by the direct chlorination or oxychlorination of ethylene. Most EDC plants are integrated with VCM plants. The VCM process generates considerable quantities of hydrogen chloride (HCl), which is then recycled in the oxychlorination process to generate more EDC. By operating both the oxychlorination and the direct chlorination pathway at the same time, the overall process eliminates the problem of hydrogen chloride disposal. This technology (often known as «balanced process») is employed in the majority of the developed regions (see figure 1 for this process).

Figure 1. Illustration of the «balanced process» of an EDC plant, using both an
oxychlorination reactor and a direct chlorination reactor.

Direct chlorination is performed in the liquid phase where liquid chlorine and pure ethylene are reacted in the presence of ferric chloride. The reaction can be carried out at either low (20-70°C) or high (100-150°C) temperatures.

The low temperature process has the advantage of low by-product formation but requires more energy to recover the EDC. The high temperature process utilises the heat of reaction in the distillation of the EDC , leading to considerable energy savings.

In the oxychlorination process, pure ethylene and hydrogen chloride, mixed with
oxygen, are reacted at 200-300°C and 4-6 bar in the presence of a catalyst, usually cupric chloride. The reaction takes place in either a fixed bed or fluid bed reactor, the latter being preferred as it is easier to control the temperature.
Some recent development in the choice of  the catalyst have been reported to produce EDC of high quality which eliminates the need for distillation.

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Dichloroethane (ethylene dichloride) – Recommanded valves :

The valves present in this process must resist corrosion.

Posted in: FAQ - Dichloroethane (ethylene dichloride)

Acetic acid – Uses of Acetic acid :

– Manufacture of acetic anhydride, cellulose acetate, vinyl acetate monomer, other acetates, acetylsalicylic acid, chloroacetic acid …
– Manufacture of pharmaceuticals, dyes, insecticides, photographic, …
– Food industry (production of fruit vinegar …)
– Textile Industry,
– Component of cleaning agent in the manufacture of semiconductors,
– Coagulant Natural Latex,
– Bacteriostatic agent (medical applications of acetic acid solutions)

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Acetic acid – Manufacturing process for Acetic acid :

Acetic Acid is a largely used industrial product, with a world demand of about 6 million tons per year. Most of the production processes are based on the carbonylation of methanol promoted by an iodine compound and catalysed by Rhodium catalyst (Monsanto process) or Iridium catalyst (Cativa process). Monsanto method was used intensively until 1996 when BP Chemicals introduced the Cativa process, which is a more efficient technology that significantly reduces the cost and produces a high quality acetic acid with very low impurity content.

Iridium-based catalyst is responsible for a series of major improvements on the carbonylation of methanol process. Being more stable allows to extend the previously limited operating conditions. For instance a highly concentrated methanol feed can be used (0.5% water) instead of a 10% water content in Monsanto. This greatly reduces the impact of the side reaction between water and carbon monoxide and consequently improves the selectivity. The overall impact is a less expensive downstream purification process of the acetic acid compared to the technology used in Monsanto process. To be more specific, the new configuration uses a compact two distillation columns configuration.The major units of a commercial scale Cativa methanol carbonylation plant are shown in the following figure.

Figure 1. Simplified process flowsheet for a Cativa-based acetic acid plant

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Acetic acid – Recommended valves :

the valves involved in the acetic acid manufacturing process have to resist to severe corrosion

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Hydrogen cyanide – HCN – Uses of Hydrogen cyanide :

Hydrocyanic acid is mainly used for the manufacture of products such as acrylonitrile, adiponitrile, cyanogen chloride, cyanuric chloride, acrylates and methacrylates, cyanide, ferrocyanide, chelating agents (EDTA, ….). It is also used as an insecticide and rodenticide, usually by fumigation.

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Hydrogen cyanide – HCN – Manufacturing process for Hydrogen cyanide :

Hydrogen cyanide (HCN) is an important chemical with over a million tons produced globally each year. The watery liquid or gas is used in a variety of syntheses including the production of adiponitrile (for nylon), methyl methacrylate, sodium cyanide and chelating agents. Most hydrogen cyanide is consumed at its production site, forming other higher-value products.

The method which has proved successful for HCN manufacture is based on that described by Andrussow in 1930 which employs methane, ammonia and air at high temperatures (1100-1200°C). Apart from the greater complexity of the recovery arrangements, the operating characteristics of the processes that are being used today are closely similar to those established by Andrussow.

The various modifications of the process differ in their sources of methane, in the proportions of reacting gases, in the nature of the platinum metal catalyst, and in the means of collecting and purifying the product, and recovering or recycling the excess ammonia. Commonly, unreacted ammonia is removed by washing with sulfuric acid. Hydrogen cyanide is then obtained as an aqueous solution by washing with water and followed by distillation and condensation. These steps are represented in figure 1

Figure 1. Flow diagram of the process for the catalytic synthesis of hydrogen cyanide from methane, ammonia and air.

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Hydrogen cyanide – HCN – Recommended valves :

depending on temperature and concentration, the valves must be made with a compatible material such as Hastelloy C (276) 316 SS.

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Hydrofluoric acid – Uses of Hydrofluoric acid

It is mainly used for the manufacture of fluorinated organic compounds, inorganic fluorides in the processing of uranium, and in the oil industry as an alkylation catalyst.

In aqueous solution, the fluoure hydrogen is used particularly in the following activities:
– Metal industry: stripping and polishing of steels and other metals
– Electronics industry: surface treatment of electronic components
– Glass industry: engraving, polishing glass, crystal, quartz purification
– Construction industry: cleaning of facades
– Analytical chemistry …

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Hydrofluoric acid – Manufacturing process for Hydrofluoric acid :

Anhydrous hydrogen fluoride (HF) and hydrofluoric acid (aqueous hydrogen fluoride) are  the basis for a variety of fluorocarbon compounds such as refrigerants, solvents, sources of raw material for production of fluoro-plastics, anesthetics, and fire extinguishing agents.

Hydrofluoric acid is manufactured by the heatingacid grade fluorspar (CaF2) with liquid sulfuric acid, forminggaseous hydrogen fluoride andsolid calcium sulfate as by-product. The endothermic reaction usually takes place in a rotary tube furnace. The entire process is kept under vacuum to help pull off the product gases and to promote HF production

The technique of heating the rotary tube furnace by means of a central combustion chamber is the usual practice today. Some technics report better energy management and conversion control by using 3 up to 15 combustion chambers with a temperature gradient (usually 300-400)C).

In general the process involves the following stages: fluorspar drying, reaction of fluorspar with sulfuric acid, hydrofluoric acid purification and scrubbing. To make high grade HF (99.98 percent pure), the crude liquid HF is reboiled and distilled

Figure 1.Simplified process flow diagram for a fluorspar plant

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Hydrofluoric acid – Recommended valves :

Carbon steel can be used as construction material for equipment related to HF at temperatures not exceeding 65°C approx. But above this temperature, it is commonly used for valves, alloys with high nickel content (eg Monel, Inconel, Incoloy, Hastelloy).

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Phosphoric acid – Uses of Phosphoric acid :

– Manufacture of fertilizers
– Surface treatment of metals
– E338 – acidity regulator / antioxidant / sequestering agent in the food industry
– Cleaning of surfaces (metal, tile, porcelain, …)
– Water treatment, petrochemical catalyst
– Coagulating the latex rubber
– Dyeing in textile industry
– Dental cement …

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Phosphoric acid – Manufacturing process for Phosphoric acid :

Phosphoric acid (H3PO4) can be produced by 3 main commercial methods: wet process, thermal process and dry kiln process. Wet process is by far the most common route and the acid can be used in phosphate fertilizers production (DAP, MAP, SPA). Thermal process phosphoric acid is of a much higher purity and is used in the manufacture of high grade chemicals, pharmaceuticals, detergents, food products, and other nonfertilizer products. The last method, using a rotary kiln, is a promising alternative because of its reduced environmental footprint and potential cost saving.

The concentration of phosphoric acid is normally expressed as % P2O5 (percent phosphoricanhydride) rather than % H3PO4 (percent phosphoric acid).
In a wet process facility (see figure 1), phosphoric acid is produced by reacting sulfuric acid (H2SO4) with naturally occurring phosphate rock. The reaction also forms calcium sulfate (CaSO4), commonly referred to as gypsum. The insoluble gypsum is separated from the reaction solution by filtration.

The operating conditions are generally selected so that the calcium sulfate will be precipitated in either the dihydrate or the hemihydrate form, thus producing 26-32% P2O5 at 70-80°C for dihydrate precipitation and 40-52% P2O5 at 90-110°C for hemihydrate precipitation. Further evaporation of the solvent can be performed for a high-concentration phosphoric acid.

Example of phosphoric acid process

Figure 1. Schematic flow diagram of a wet process plant (phosphoric acid process)

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Phosphoric acid – Recommended valves :

Industrial phosphoric acid solutions are very aggressive due to impurities coming from natural phosphate rocks. Pumps and valves must be made of corrosion resistant alloys such as super-austenitic stainless steel (AISI 904L or Uranus B6, Hastelloy, Incoloy, Inconel) or high chromium content.

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Sulfuric acid – Uses of Sulfuric acid :

– Manufacture of phosphoric acid and fertilizers
– Raw material for the manufacture of many chemicals (alcohol, mineral sulfates, detergents, …)
– Petroleum, textile, paper and pulp industry, pharmaceutical industry
– Treatment of metals – Batteries …

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Sulfuric acid – Manufacturing process of Sulfuric acid :

Sulfuric acid is the largest-volume industrial chemical produced in the world (200 million tons per year). Concentrated sulfuric acid (93-98 %) is used in the manufacture of fertilizers, explosives, dyes, and petroleum products.

The starting material for sulfuric acid manufacture is clean, dry sulfur dioxide (SO2) gas. This can be obtained by burning molten sulfur, from metallurgical off-gases or by decomposing spent sulfuric acid.
Over the last decades the contact process has been used to produce sulfuric acid, replacing the traditional «Lead Chamber» process dating back to the 18th Century.

In the contact process SO2 is oxidized to sulfur trioxide (SO3) at high temperature (about 450°C) in the presence of a vanadium catalyst. SO3 then is dissolved in concentrated sulfuric acid forming fuming sulfuric acid (oleum). This can then be reacted safely with water to produce concentrated sulfuric acid.

Major changes have been made in process and plant design to maximize energy recovery and then use this heat to generate high-pressure steam and/or electricity. The older «single absorption» process has been largely replaced by the «double absorption» process which increases yield of acid and reduces emissions. A typical flowchart for a double absorption sulfuric acid plant is shown in figure 1.

Example of sufuric acid process

Figgure 1. Example of schematic sulfuric acid process

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Sulfuric acid – Recommended valves :

Depending on the temperature range and the concentration of the acid, common used compatible materials for the valves are Alloy 276, Alloy 20, Hastelloy B-3 and Tantaline

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PBT – Uses of PBT :

– Insulating material for high temperature and high stress
– Boxes contactors
– Switches
– Household appliances
– Gear

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PBT – Manufacturing process of PBT :

PBT (polybuthylene terephthalate) emerged on the market towards the sixties as a raw material for synthetic fibers and engineering plastics. It belongs to the group of linear, saturated polyesters. PBT faces inter-material competition from other thermoplastics with similar properties such as polyacetal, nylon or other terephthalic polymers (PET, PTT).

The main raw materials used to manufacture PBT are 1,4-butanediol (BDO), dimethyl terephthalate (DMT), purified terephthalic acid (PTA) and catalysts. Hitachi, Uhde Inventa-Fischer, and Lurgi Zimmer AG are the main licensors of PBT technology and cover the full spectrum of process variations (DMT vs PTA route,batch vs continuous).

There are different design variations that go from a 5-Reactor (5-R) to a compact 2-Reactor (2-R) configuration. Recent technologies (Zimmer COMBI reactor, Uhde Inventa-Fischer ESPREE and DISCAGE reactors) propose a 2-R design by combining the esterification and pre-polycondensation into one reactor, thus reducing the overall investment. As an example, the Zimmer 2-R process is illustrated in the figure 1 below.

Example of PBT manufacturing process

Figure 1. Zimmer continuous PBT process (PTA route). During the reaction, THF and water are also produced under elevated temperature and reduced pressure

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PBT – Recommended valves :

Each step of the production process of PBT has undergone many improvements over the years. Design development, research of catalysts and optimization of special valves for PBT continues today.

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PE – Polyethylene – Uses of Polyethylene (PE) :

Plastic packaging : plastic bags, bottles of milk, lots of toys ….

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PE – Polyethylene – Manufacturing process of Polyethylene (PE) :

Polyethylene (PE) is the most common polymer in the world, produced 85mt / year. This is mainly due to the wide range of possible uses. Depending on its melting point, the PE is divided into several categories: low, medium and high density, each class with specific industrial applications. It occurs in the following forms: high density polyethylene (HDPE), ULDPE (ultra low density polyethylene), LLDPE (linear low density polyethylene), MDPE (medium density polyethylene) HMWPE polyethylene (high molecular weight) and UHMWPE (ultra high molecular weight).

Traditionally, the polymerization was taking place under high pressure (several hundred bars) and high temperature (up to 300°C) but over the years the energy input has been reduced by using catalytic systems. The Ziegler and metallocene catalyst families have proven to be very flexible at copolymerizing ethylene with other olefins and have become the basis for the wide range of polyethylene resins available today, including very low density polyethylene and linear low-density polyethylene.

Polyethylene is mostly produced in slurry, gas-phase fluidized bed reactor or combination of both processes in series (such as like Spherilene and Borstar processes). Either double-tube loop reactors or autoclaves (stirred-tank reactors) are commercially employed for slurry-phase polymerization, in the presence of a catalyst system and a diluent.
The following image illustrates one of the slurry process configurations using a Double-Tube Loop Reactor followed by a gas phase reactor (Borstar process).

Example of PE manufacturing process

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PET – Uses of PET :

– la fabrication de bouteilles, flacons recyclables
– Fibres textiles dites polaires
– Rembourrage de peluches, de coussins

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PET – Manufacturing process of polyethylene Terephtalate (PET) :

Polyethylene Terephthalate (PET) is one of the major polymers produced worldwide representing about 18 % of world polymer production and comes in third after Polyethylene and Polypropylene. The main downstream industries based on PET are production of polyester fibers, accounting for around 65% of global consumption, and PET bottle resins consuming around 30%.
PET is produced from high purity ethylene glycol (EG) and Terephthalic acid (TPA).  All PET resin manufacture processes are using the same reaction path as shown in the figure bellow :

The conventional PET process consists of two discrete plant sections. The first part consists of melt phase reaction used to produce copolymers with an intrinsic viscosity (IV) suitable for textile applications. But when very high molecular weights are desired, as is the case for bottle grade PET resins, the polymerization may be carried out in stages. The traditional Buhler process integrates four typical stages for producing bottle grade PET : crystallization, annealing, solid state polymerization (SSP) and cooling. New technologies are currently replacing this design with a tendency to reduce the number of units involved
and thus the global process cost.

A radical approach that is rapidly becoming more and more employed is Eastman IntegRex technology (illustrated in figure 2). The main unit is a tubular reactor that leads to a significant reduction of energy, raw materials consumptions, operation costs and capital costs.

Example pf Eastman IntegRex PET technology

Figure 2. Eastman IntegRex manufacturing technology

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PET – Recommended valves :

To prevent polymerization of the fluid, the valves should mostly be equipped with heating jacket and resist severe corrosion.

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PP – Polypropylene – Uses of PP (Polypropylene) :

This polymer associated with others allows multiple uses and has the advantage of being easily recyclable. The polypropylene is used in the automotive, polypropylene plastic is most commonly used than the PVC, the polyethylene and the polyurethane. We can find it for example in the wiper motors, bumpers, the locking device trunks, dashboards, empty pockets, carpets … In appliances, tanks and bases of washing machines include polypropylene … In packaging its use remains relatively low, with only 7% of plastics used in this sector includes polypropylene It is also found in toys, luggage, fibers …

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PP – Polypropylene – Manufacturing process of PP (Polypropylene) :

Polypropylene is currently one of the fastest growing polymers. Much of this growth is attributed to polypropylene’s ability to displace conventional materials (wood, glass, metal) and other thermoplastics at lower
cost. Polypropylene (PP) is a tough, rigid plastic and produced in a variety of molecular weights and crystallinities.

Polypropylene is made from the polymerization of propylene gas in the presence of a catalyst system, usually Ziegler-Natta or metallocene catalyst. Polymerization conditions (temperature, pressure and reactant concentrations) are set by the polymer grade to be produced.

Various production processes exist with some general similarities. They are taking place either in a gas-phase (fluidized bed or stirred reactor) or a liquid-phase process (slurry or solution). An example of flow diagram corresponding to each of the two types of processes is illustrated in figure 1 bellow. The gas-phase polymerization is economical and flexible and can accommodate a large variety of catalysts. It is the most common technology in modern polypropylene production plants. Relevant technologies are Novolen®, Unipol® (gas-phase processes), Borstar® and Spheripol® (liquid-phase processes).

Figure 1a : PP gas-phase process example

Figure 1b: PP liquid-phase process example.

The obtained powder is finally conveyed to powder silos and then converted into pellets that incorporate a full range of
well-dispersed additives.

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PP – Polypropylene – Recommended valves :

Guichon Valves offers valves specially designed for viscous liquids and designed to minimize pressure drops and dead zones. Jacketed valves allow to maintain the fluid temperature to prevent solidification. Sealants (gaskets, seals, etc …) are selected to prevent pollution of the circulating fluid.

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Polycarbonate (PC) – Uses of PC :

– Lens
– CD and DVD
– Lens thermal camera (infrared camera)
– Auto Headlights

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Polycarbonate (PC) – Manufacturing process of PC :

Polycarbonate (PC) is an engineering plastic with outstanding transparency, impact resistance, and heat resistance. These unique properties have resulted in applications such as bulletproof windows, unbreakable lenses, compact discs, etc. About 2.7 million tons of polycarbonate are produced annually worldwide.

The most common manufacturing process is based on the reaction of bisphenol A (BPA or Bis-A) and phosgene in the interfacial polymerization process. Here, disodium saltof BPA dissolved in water reacts with phosgene dissolved in a chlorinated organic solvent such as CH2Cl2 (methylene chloride). However, the phosgene process entails a number of drawbacks including the toxicity of phosgene, the use of low-boiling-point solvent, and the large quantity of waste water containing methylene chloride which must be treated. The use of concentrated sodium hydroxide and hydrogen chloride adds the problem of corrosion that should be considered.

Figure 1.Overall reaction path to Polycarbonate (PC) using phosgene process and non-phosgene process

Figure 1.Overall reaction path to Polycarbonate (PC) using phosgene process and non-phosgene process

Nowadays, the production and use of phosgene in the factories have been very severely restricted worldwide. There are aSabic Innovative Plastics (formerly GE Plastics), Bayer, and Asahi/Chi Mei have independently developed and are using non-phosgene processes. They all take the same overall approach where polymerization relies on the transesterification of diphenyl carbonate (DPC) with bisphenol A. This is more commonly termed as the melt process which has the advantage of making a product undiluted form that may be pelletized directly. Disadvantages include the need for equipment to withstand high temperatures and high vacuum. With lower plant construction costs and lower feedstock costs, it is anticipated that this kind of non-phosgene process will be widely adopted for PC production throughout the world.

Example of Polycarbonate manufacturing process

Fig 2. Polycarbonate (PC) process using phosgene,most currently used

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Polycarbonate (PC) – Recommended valves :

Guichon Valves offers valves specially designed for viscous liquids and designed to minimize pressure drops and dead zones. Jacketed valves allow to maintain the fluid temperature to prevent solidification. Sealants (gaskets, seals, etc …) are to Selected to prevent pollution of the circulating fluid.

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Polyurethane – Uses of Polyurethane :

– Elastomers: Condoms, Surgical Glove
– Paintings for all types of surfaces
– Adhesives for outdoor use
– Fibers: Cushion, clothing, swim suit

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Polyurethane – Process de fabrication du Polyurethane :

Polyurethanes, also known as polycarbamates, are some of the most versatile polymers. First developed in late 1930s,they are used in building insulation, surface coatings, adhesives, and solid plastics. Polyurethanes can be produced in four different forms including elastomers, coatings, flexible foams, and cross-linked foams. Each one has specific uses based on theirs properties.

Polyurethanes are produced by reacting an isocyanate and apolyol of various types (most common isocyanates: TDI (toluenediisocyanate) and MDI (methylenebisdiphenyldiisocyanate); mostcommon polyols: PTMEG (polyetetramethylene ether glycol), PPG (polypropylene ether glycol)).

During this process, the raw materials are pumped from their own storage tank to a common mixing vessel kept under controlled pressure and temperature. Here, additives are incorporated in accordance with a specific recipe. The temperature control inside the reacting vessels is usually made by a recirculating system such as the one illustrated in figure 1.

Exemple de schéma de fabrication du Polyuréthane

Figure 1.Schematic of a high-pressure vessel with re-circulation system (a: feed tanks, b: metering pumps, c: mixhead, d: safety valve, e: recirculation throttle, f: low-pressure recirculation valve, g: filter, h: hydraulics for mixhead, M: drive motor)

Polyurethane foam is the most widely used flexible foam plastic. It is produced by adding a blowing agent such as carbon dioxide and methylene chloride. Hard polyurethane plastic can be formed if the polymerization reaction is carried out without blowing agent. In some applications, continuous systems are a good alternative to the batch polyurethane production process, as it can reduce the risk of failed batches.

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Polyurethane – Recommended valves :

Guichon Valves offers valves specially designed for viscous liquids and designed to minimize pressure drops and dead zones. Jacketed valves allow to maintain the fluid temperature to prevent solidification. Sealants (gaskets, seals, etc …) are selected to prevent pollution of the circulating fluid.

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PVC – Polyvinyl chloride – Uses of Polyvinyl chloride (PVC) :

Polyvinyl chloride (PVC) is the third-most widely produced plastic, after polyethylene and polypropylene. PVC is used in the building and construction industry,consumer goods and packaging. At global level, demand for PVC exceeds 35 million tons per year and it is in constant growth.

Posted in: FAQ - PVC - Polyvinyl chloride

PVC – Polyvinyl chloride – Manufacturing process of Polyvinyl chloride (PVC) :

PVC is produced by polymerization of vinyl chloride monomer (VCM). The main polymerization methods include suspension, emulsion, and bulk (mass) methods. About 80% of production involves suspension polymerization. First, the raw material VCM is pressurized and liquefied, and then fed into the polymerization reactor, which contains water and suspending agents in advance. Next, the initiator is fed into the reactor, and PVC is produced under a few bars at 40 – 60°C.
The role of water is to remove and control the heat given off in the polymerization process. PVC forms as tiny particles which grow and when they reach a desired size the reaction is stopped and any unreacted vinyl chloride is distilled off and re-used. The PVC is separated off and dried to form a white powder also known as PVC resin (see flow diagram).
Emulsion polymerization produces finer resin grades having much smaller particles, which are required by certain applications.

Example of the PVC manufacturing process.

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PVC – Polyvinyl chloride – Recommended valves :

Guichon Valves offers valves specially designed for viscous liquids and designed to minimize pressure drops and dead zones. Jacketed valves allow to maintain the fluid temperature to prevent solidification. Sealants (gaskets, seals, etc …) are selected to prevent pollution of the circulating fluid.

Posted in: FAQ - PVC - Polyvinyl chloride

Epoxy resins – Uses of Epoxy resins :

Epoxy resins are thermosetting polymers containing epoxide groups.Applications for epoxy resins are extensive: adhesives, bonding, construction materials (flooring, paving, and aggregates), composites, laminates, coatings and molding.

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Epoxy resins – Manufacturing process of Epoxy resins :

Most common epoxy resins are produced from a reaction between epichlorohydrin (ECH) and bisphenol-A (BPA), though the latter may be replaced by other raw materials (such as aliphatic glycols, phenol and o-cresol novolacs) to produce specialty resins.
The epoxy resins can be obtained in either liquid or solid states. The two processes are similar. Firstly ECH and BPA are charged into a reactor. A solution of 20-40% caustic soda is added to the reaction vessel as the solution is brought to the boiling point. After the evaporation of unreacted ECH, the two phases are separated by adding an inert solvent such as methylisobutylketone (MIBK). The resin is then washed with water and the solvent is removed by vacuum distillation.The producers will add the specific additivesto create a formula that lend special properties such as flexibility, viscosity, color, adhesiveness, and fastercuring, depending on a particular application.

In order to convert epoxy resins into a hard, infusible, and rigid material, it is necessary to cure the resin with hardener. Epoxy resins can cure at practically any temperature from 5-150oC depending on the choice of curing agent. Primary and secondary amines are widely used to cure epoxy resins.

Epoxy resin manufacturing process with flow chart

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Alumina – Uses of Alumina :

– The main raw material for the production of aluminum
– Manufacture of refractory and ceramic

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Alumina – Manufacturing process of Alumina :

Alumina, synthetically produced aluminum oxide (Al2O3), is a white crystalline substance that is used as a starting material for the production of aluminum metal. The world-wide production is close to 90 million tons of alumina per year.

The Bayer process is the principal industrial means of refining bauxite to produce alumina. In the Bayer process, bauxite ore (containing 30 – 55% Al2O3), is digested by washing with a hot solution of sodium hydroxide at 175°C. The slurry is then filtered and sent to a rotary kiln calciner to dry and, under very high temperature (1000°C), is transformed into the fine, white powder known as alumina. A large amount of the aluminum oxide so produced is then subsequently smelted in the electrolytic process in order to produce aluminum.

Example of Alumina manufacturing process

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Alumina – Recommended valves :

Guichon Valves offers specially designed valves suited for this kind of severely erosive slurry and abrasive application.
Internal lining, stem protection, wear-resistant stellited materials can be specified, depending on the type of the valve (seat, ball) and the customer’s needs.

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Molten salts – Chemical formula :

– Hydroxydes : NaOH, KOH, NaOH-KOH, etc…
– Nitrates : KNO3-NaNO2-NaNO3, etc…
– Carbonates : Na2CO3, K2CO3, Li2CO3-K2CO3, Na2CO3, etc…
– Fluorides : LiF-NaF-KF, etc…
– Chlorides : NaCl, KCl, CaCL2, Li-Cl-KCl, ZnCl2, etc…
– Etc…

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Molten salts – Uses of Molten salts :

– Bath salt for various heat treatments of alloys: cyanide salts, chloride and fluoride (cryolite)
– Production of reactive metals, and refractory metals
– Heat transfer fluids and thermal storage (fluoride, chloride and nitrate)

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Molten salts – Manufacturing process of Molten salts

Molten or fused salt technology includes some very diverse applications. Interest in the use of molten salts in industrial processes is continually increasing and these media are gradually becoming accepted as a normal field of chemical engineering. In the heat treating industry, molten salts are commonly used as amedium for heat treatment of metals and alloys as well as for surface treatment. In nuclear and solar energy systems, they have been used as a medium for heat transfer and energy storage. Other applications include extraction of metals and high-temperature batteries and fuel cells.

All of these technologies are linked by the general characteristics of molten salts:
– Good heat transfer capacity
– Can attain very high temperatures (> 700°C)
– Can conduct electricity

Molten salts have been used in many industries as a high temperature heat transfer medium. Depending on the temperature needed for a specific application, the molten salts can categorized as showed in the following table :

Molten salts temperature table

The steam production of steam in solar thermal power plants is a good example of how molten salts can be used as heat transfer fluids (see following figure):

Application of Molten salts

Operating at near atmospheric pressures reduces the mechanical stress endured by the system, thus simplifying aspects of design.
The containment material, which is in contact with the molten salt, is sometimes subject to corrosion. However the corrosion rate is strongly related to the type of molten salt, to the operating temperature as well as the velocity of the fluid. A coted alloy maybe needed.

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Molten salts – Recommended valves :

Guichon Valves offers special designed valves Valves relying on long stems and graphite packing for the seals usually behave well in molten salts medium and very high temperature.

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Potassium fertilizers – Chemical formula :

Potassium chloride KCl, Potassium sulfate K2SO4

Posted in: FAQ - Potassium fertilizers

Potassium fertilizers – Uses of Potassium fertilizers :

Potassium fertilizers are mainly used as fertilizer and marginally as a food additive (acidity regulator E515)

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Potassium fertilizers – Manufacturing process of Potassium fertilizers

Potassium is the third major plant and crop nutrient after nitrogen and phosphorus. Potash is the common name for various mined and manufactured salts that contain potassium. Today, potash is produced worldwide at amounts exceeding 30 million tons per year. Potassium chloride (KCl) accounts for most of the K used in world agriculture (about 90%). Other widely used K products include potassium sulfate, potassium nitrate, and potassium-magnesium salts.

Potassium bearing minerals are mined from underground ore deposits, salt lakes and brines. Then, the ore must be beneficiated and purified using dry and slurry processes. Guichon Valves can supply custom-made valves suitable for such abrasive slurries.

The majority of mined KCl is used for obtaining various grade fertilizers based on the particle size (granular, standard, fine, soluble). Granular KCl is often applied in mixtures with other N and P based
fertilizers to provide, in one application, the nutrients required by the crops.

Another potassium fertilizer is potassium sulfate, which is frequently used for crops where additional chloride from more common KCl fertilizer is undesirable. Potassium sulfate can be extracted from the mineral langbeinite or it can be synthetized by treating potassium chloride with sulfuric acid at high temperature. By adding magnesium salts to potassium sulfate, a granular potassium-magnesium compound fertilizer can also be produced.

Potash — A Simplified Flow Diagram

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Phosphate fertilizers – Chemical formula :

Calciums phosphate Ca3 (PO4) 2, aluminum phosphate, ammonium phosphate (NH4)3PO4

Posted in: FAQ - Phosphate fertilizers

Phosphate fertilizers – Manufacturing process of Phosphate fertilizers

Phosphate rock (PR) is the raw material used in the manufacture of most commercial phosphate fertilizers on the market. With access to large, high-quality reserves of
phosphate rock, Morocco, China and US are the most important players in phosphate industry.

Ground phosphate rock from the mines is first sent to recovery units to separate sand and clay and to remove impurities. Most of the processes are wet to facilitate material transport and to reduce dust.

A weak phosphoric acid (40-55%) is produced from the reaction of PR with sulfuric acid, using a wet- process. The obtained phosphoric acid is then used in the production of a series of liquid or solid fertilizers. The most important ones are single and triple superphosphates (SSP, TSP) and ammonium phosphates (MAP, DAP). Usually the plants are using flexible process technologies, allowing the manufacture of at least two products with interchangeable lines (e.g. TSP and DAP combination).

SSP is simple to produce but is nowadays less popular. TSP results from the reaction of PR with phosphoric acid, using the common Dorr-Oliver slurry granulation process. GTSP (granulated TSP) is obtained in this way, with very good storage and handling properties.

Economical and with high nutrient content, ammoniated phosphates such as mono- and di-ammonium phosphate (MAP, DAP) are another popular choice of fertilizers. They are obtained when ammonia (liquid or gaseous) is added to the weak phosphoric acid.

Phosphate fertilizers production flow-cart can be illustrated in the following figure :

Example of the phosphate fertilizers process

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Phosphate fertilizers – Recommended valves :

Corrosive conditions caused by acids such as phosphoric and sulfuric acid impose an extra care when choosing the suitable materials for the equipment as valves for example. Depending on the rock impurity content, fluoride and chloride influence can also be considered.

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Nitrogen fertilizers – Chemical formula :

Anhydrous ammonia (NH3),Ammonium sulfate (NH4) 2SO4, ammonium nitrate (NH4NO3)

Posted in: FAQ - Nitrogen fertilizers

Nitrogen fertilizers – Uses of Nitrogen fertilizers :

Nitrogen fertilizers are the most commonly used fertilizer in agriculture

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Nitrogen fertilizers – Manufacturing process of Nitrogen fertilizers :

Nitrogen fertilizers represent a major industry worldwide accounting for nearly 100 million tons of various products per year. Nitrogen fertilizers include many types of liquid and solid products, among which the most common ones are ammonia, ammonium nitrate, and urea.

Ammonia is produced by reacting nitrogen from the air with hydrogen from natural gas at high pressure and temperature using the Haber process (200-300 bars and around 450°C). Anhydrous ammonia is stored as a liquid under pressure or refrigerated. For ease of handling, it is often converted to other types of fertilizers (see the following flow chart).

Example of nitrogen fertilizers process

As a first step, nitric acid is produced by mixing ammonia and air in a tank followed by the absorption of the nitric oxide gas in water. Concentrated nitric acid (50 to 70 %) and ammonia gas are then mixed together in a tank and a neutralization reaction occurs at 100-180°C, producing ammonium nitrate.

Another important nitrogen-based fertilizer is the urea, which is produced by a reaction of ammonia with carbon dioxide at high pressure. Both ammonium nitrate and urea can be further concentrated and converted into a solid form (prills or granules). Another process step can combine urea with ammonium nitrate solution to make liquid urea ammonium nitrate or UAN.

Equipment failure because of nitric acid corrosion can be avoided by the use of austenitic stainless steel.

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Liquid sulfur – Uses of Liquid sulfur :

Sulfur is used for manufacturing sulfuric acid, fertilizers, pesticides and rubber products.

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Liquid sulfur – Manufacturing process of Liquid sulfur :

Today, sulfur is produced from petroleum, natural gas, and related fossil resources, from which it is obtained mainly as gaseous hydrogen sulfide (H2S). In petroleum refineries, gases with an H2S content of over 25% are suitable for recovery of sulfur in Claus plants.

The Claus process (see figure 1) is the most significant gas desulfurizing process, recovering elemental sulfur from gaseous hydrogen sulfide.  This process is divided into two main steps, thermal (in burners above 850°C) and catalytic. The catalytic recovery of sulfur consists of three sub steps:
– Reheating: the gas is reheated and introduced to the catalyst bed.
– Catalytic reaction: the remaining H2S is reacted with SO2 at lower temperatures (about 200-350°C) over a catalyst to make more sulfur. The reaction does not go to completion even with the best catalyst. For this reason two or three reactors are used.
– Cooling and condensation: In the sulfur condensers, the process gas coming from the burner and from the catalytic reactors is cooled to between 150 and 130°C, sulfur being removed between each stage.

Figure 1. Schematic flow diagram of a straight-through, 3-reactor Claus sulfur recovery unit

Figure 1. Schematic flow diagram of a straight-through, 3-reactor Claus sulfur recovery unit

Over the years many improvements have been made to the Claus process in order to adapt it to different feed gas compositions (e.g. high content of CO2 or ammonia) and in order to improve its effectiveness (conversion, energy balance, installation cost). Most sulfur recovery plants utilize one of three basic variations of the Claus process «straight-through», «split-flow» or «direct-oxidation».

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Ethylene cracking – Chemical formula :

Ethane = Ethylene + Hydrogen
C2H6 = C2H4 + H2
Ethylene = C2H1

Posted in: FAQ - Ethylene cracking

Liquid sulfur – Recommended valves :

This process shows to be very aggressive for the valves which have to be generally in alloy materials.

Posted in: FAQ - Liquid sulfur

Cracking process – Recommended valves :

The contraints related to steam cracking are :
1 – The thermal cracking (Delayed cocking units) phase of the process generates effluent with coke particules. It could be the same issues in case of Steam cracking (Ethane/Ethylene process)
2 – The decoking phase of the process generates coke particules which can drop into the valve body during the opening-closing phase and damage the sealing system.
Guichon Valves proposes a valve design with sliding gate and sleeve combination or double discs and substitution rings to reduce ingress of coke particules. The third generation of Guichon Valves’s transfer Line Valves, TLV0 (Transfer Line Valve), provides reliable, long lasting tight shut-off.

Posted in: FAQ - Ethylene cracking

Fluid Catalytic Cracking (FCC) – Recommanded valve :

The main requirements of FCC applications are :
– resistance to abrasion
– high temperature suitability
– long life and reliability

Guichon produces valves with all weldable high temperature materials, also ceramic, concrete and full stellite linings allowing for longer service and improved safety.

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PTA (Terephthalic acid) – Uses of PTA

– Polyester fibers based on PTA both alone and in blends with natural and other synthetic fibers.
– Polyester films based on PTA are used in audio and video recording tapes, data storage tapes, photographic films, labels and other sheet material.
– Raw material for production of polyethylene terephthalate (PET), which is the main PTA derivative.
– Pharmaceutical industry : raw material for drugs.
– Raw material for production of polyesters used in fabrication of powder and water-soluble coatings.

Posted in: FAQ - PTA (Terephthalic acid)

PTA (Terephthalic acid) – Manufacturing process of PTA

Modern technologies produce purified terephthalic acid by the catalytic liquid phase oxidation of paraxylene in acetic acid, in the presence of air. The process uses manganese or cobalt acetate as a catalyst. The reaction is exothermic, producing water which is removed in a solvent recovery system. Acetic acid from this is returned to the reactor together with the oxidation catalyst. The resulting PTA is purified in a crystalliser where the unreacted xylene and water are flashed off.

It exists several process licensed by : BP (Amoco), Advansa (ICI), Dow (Inca), Mitsubishi, Eastman and Mitsui. The figure below presents the simplified process of Hitachi :

Posted in: FAQ - PTA (Terephthalic acid)

PTA (Terephthalic acid) – Recommanded valve :

Guichon Valves offers valves for PTA application designed to minimize dead zones to avoid the storage of the PTA. The materials used with this type of acid are high value and are part of the knowledge Guichon Valves manufacturing processes, concentration levels of various oxydizing, mechanical strength, etc …

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Caprolactam – Uses of Caprolactam

Caprolactam is primarily used in the manufacture of synthetic fibers (especially Nylon 6). Caprolactam is also used in production of :
– brush bristles,
– textile stiffeners,
– film coatings,
– synthetic leather,
– plastics and plasticizers,
– paint vehicles,
– cross-linking for polyurethanes,
– lysine (synthesis).

Posted in: FAQ - Caprolactam

Caprolactam – Manufacturing process of Caprolactam

Caprolactam is an organic compound, this colourless solid is a lactam or a cyclic amide of caproic acid. Approximately 4.5 billion kilograms are produced annually. Caprolactam is the precursor to Nylon 6, a widely used synthetic polymer. Firstly, Caprolactam was prepared by the cyclization of ε-aminocaproic acid, the product of the hydrolysis of caprolactam. Given the commercial significance of Nylon-6, many methods have been developed for the production of caprolactam :

Most of the caprolactam is synthesised from cyclohexanone, which is first converted to its oxime. Treatment of this oxime with acid induces the Beckmann rearrangement to give caprolactam.

The immediate product of the acid-induced rearrangement is the bisulfate salt of caprolactam. This salt is neutralized with ammonia to release the free lactam and cogenerate ammonium sulfate. In optimizing the industrial practices, much attention is directed toward minimizing the production of ammonium salts.

The other major industrial route involves formation of the oxime from cyclohexane using nitrosyl chloride. The advantage of this method is that cyclohexane is less expensive than cyclohexanone.

The immediate product of the acid-induced rearrangement is the bisulfate salt of caprolactam. This salt is neutralized with ammonia to release the free lactam and cogenerate ammonium sulfate. In optimizing the industrial practices, much attention is directed toward minimizing the production of ammonium salts.

The other major industrial route involves formation of the oxime from cyclohexane using nitrosyl chloride. The advantage of this method is that cyclohexane is less expensive than cyclohexanone.

Posted in: FAQ - Caprolactam

Caprolactam – Recommanded valve :

Guichon Valves offers valves for Caprolactam application specially designed for viscous liquids and designed to minimize pressure drops and dead zones. Jacketed valves allow to maintain the fluid temperature to prevent solidification of caprolactam. Sealants (gaskets, seals, etc …) are selected to prevent pollution of the caprolactam.
In case of powder transport, Guichon Valves offers solutions to prevent abrasion.

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Titanium Dioxide-TiO2 – Uses of Titanium Dioxide :

Titanium dioxide (TiO2) is a simple inorganic compound produced as a pure white powder. More than 50 % of the titanium dioxide is used in paints, varnishes and lacquer. It also is used in coatings, paper and plastics industries with total worldwide sales of around 4.5 million tons per year.

Posted in: FAQ - Titanium Dioxide-TiO2


Polyethylene is a polyolefin which is an high molecular weight hydrocarbon. These are the only plastics that have a lower specific gravity than water. The main properties of polyethylene are to be weatherproof, easy to process, low cost and to warranty a good chemical resistance.
When ethylene is polymerized the result is relatively straight polymer chains. From the main chain they can branch out. We get different kinds of Polyethylenes from the varying degree of branching in their molecular structure.

– LDPE (Low Density Polyethylene) has the most excessive branching. This causes the low density to have a less compact molecular structure which is what makes it less dense. It has a density of 0.910-0.925 g/cm3. LLDPE (Linear Low Density Polyethylene) has a significant numbers of short branches. Because it has shorter and more branches its’ chains are able slide against each other upon elongation without becoming entangled like LPDE which has long branching chains that would get caught on each other. This gives LLDPE higher tensile strength and higher impact and puncture resistance than the LDPE. It has a density of 0.91-0.94 g/cm3.
Low Film for packaging is one of the largest markets for low density polyethylene (LDPE/LLDPE). Others applications are : squeeze bottles, toys, carrier bags, high frequency insulation, chemical tank linings, heavy duty sacks, general packaging, gas and water pipes.

– HDPE (High Density Polyethylene) has minimal branching of its’ polymer chains. Because it is denser it is more rigid and less permeable then the LDPE. It has a density of 0.941-0.965 g/cm3. Applications of HDPE are : chemical drums, jerricans, carboys, toys, picnic ware, household and kitchenware, cable insulation, carrier bags, food wrapping material. Low cost, high rigidity and ease of blow moulding has made the material a natural choice in gardening furnishings.

– Some others polyethylene could be find and are commonly used : MDPE (Medium Density Polyethylene), UHMWPE (Ultra High Molecular Weight Polyethylene) and XLPE (Crosslinked Polyethylene).


Titanium Dioxide-TiO2 – Manufacturing process of Titanium Dioxide :

Manufacture takes place by either the sulfate process or the chloride process and the main raw materials include ilmenite (FeO/TiO2), naturally occurring rutile, or titanium slag. In essence the process converts the impure TiO2 feedstock into an easy to purify intermediate, separates out the impurities then converts back to pure TiO2 (see figure 1).

TiO2 manufacturing process

Because of significant environmental and cost issues associated with the sulfate process, most new manufacturing plants are based on the chloride process. The quantity of waste materials is thus reduced compared to the older sulfate process. However, the chloride process is more difficult to operate. The extreme corrosiveness of the high temperature chlorine (900 – 1000°C) employed in the process contributes to the difficulty.

Posted in: FAQ - Titanium Dioxide-TiO2

LDPE-LLPDE-HDPE – Manufacturing process of LDPE,LLPDE,HDPE

The LDPE process consists in five operations :
– The compression of gas : Gaseous ethylene is supplied and melted with a part of unreacted gas from the process in oreder to be compress in the first reactor.This new compressed gas is melted again with unreacted gas and compress in the second compressor.
– The polymerization : An initiator (organic peroxide) is added to the second compressed gas into the reactor and the materials are mixed inside the reactor through stirrer . Polymerization is obtained in the reactor at a certain pressure and temperature.
– The separation of gas : The unreacted gas is then separated by 3 levels of separators. Those unreacted gas will be injected before the compressor, notice than a part will be exclude from the process.
– The extrusion : Once the unreacted gas is removed, the polymers can be extruded and pelletized.
– The storage and packaging : The pellets are dried through a dryer and classified pellets by pellet size. The degassing is done by hot air injection.


The HDPE process consists of :
– Polymerization : Ethylene monomers are polymerized in solvent together with catalyst, hydrogen and comonomer. The polymerization heat is cooled through external circulation heat exchanger. The reacted slurry is transferred to the separation/drying process.
– Separation/Drying : Slurry is transferred to a high-speed centrifuge from which it is separated into solvent and wet powders. The separated solvent is supplied to the reactor and some solvents are recycled in the process through refining. Wet powders are transferred to the powder dryer and dried.
– Transfer/Extrusion : The wet powders are dried in the powder dryer by evaporating the solvent with high-temperature nitrogen and steam. The evaporated solvent is recovered by the scrubber. The dried powders are transferred to the extrusion process where they are melted and pelletized in the extruder. Then they are transferred to the storage silo.
– Storage & Packaging : The products transferred to the pellet silo are cooled by air and homogenized.


Titanium Dioxide-TiO2 – Recommended valves :

For this kind of acidic and corrosive media, Tantaline valves offer a corrosion resistance beyond nickel alloys (Hastelloy), titanium (Ti) and zirconium (Zr).

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LDPE-LLPDE-HDPE – Recommanded valve :

Guichon Valves offers valves for polyethylene production specially designed for viscous liquids and designed to minimize pressure drops and dead zones. Jacketed valves allow to maintain the fluid temperature to prevent solidification of polyethylene. Sealants (gaskets, seals, etc …) are to Selected to prevent pollution of polyethylene.
Guichon Valves offers specially designed valves suited for abrasive application like powder and pellets.