Market Segments

Industrial Inorganic Chemicals
The graphics below represent various operational units found within Inorganic Chemical manufacturing facilities

Deionization - Twin Bed

Neutralization

Chemical Injection

Wastewater Treatment

Fume Scrubbing

Batch Control

Process Description

Manufacturing inorganic chemicals involves many diverse processes to produce a wide variety of end products, including various degrees of purity and concentrations for each one. Table 1 lists a sampling of inorganic chemicals with widespread use in various industries. Table 2 lists some of the more common inorganic chemicals and provides a brief description of the primary method used to manufacture those chemicals.

Table 1
Acetic Acid	Barium Sulfite	Ferric Chloride	Manganese Iodide	Selenic Acid
Adipic Acid Solution	Bismuth Oxychloride	Ferric Fomate Ferric Nitrate	Manganese Lactate	Silicic Acid
Aluminum Bromate	Boric Acid	Ferric Oxalate	Manganese sulfate	Silicon Fluoride
Aluminum Bromide	Bromic Acid	Ferric Sulfate	Mercurous Nitrate	Silver Nitrate
Aluminum Chloride	Bromine Water	Ferric Sulfide	Nickel Bromide	Silver Perchlorate
Aluminum Fluoride	Cadmium Bromate	Ferric Thiocyanate	Nickel Chloride Nickel Formate	Silver Permanganate
Aluminum Hydroxide	Cadmium Bromide	Ferrous Chloride	Nickel Nitrate	Silver Thiosulfate
Aluminum Iodide	Calcium Bisulfite	Ferrous Chloroplatinate	Nickel Potassium Cyanide	Sodium Acetate
Aluminum Nitrate	Calcium Bromate	Ferrous ferricyanide	Nitric Acid	Sodium Bicarbonate
Aluminum Sodium Chloride	Calcium Bromide	Ferrous Fluoride	Palladium Chloride	Sodium Bisulfate
Aluminum Sulfate	Calcium Carbonate	Ferrous Formate	Platinic Acid	Sodium Bromide
Alum	Calcium Chlorate	Ferrous Iodide	Platinum Chloride	Sodium Carbonate
Ammonia	Calcium Chloride	Ferrous Perchlorate	Platinum Sulfate	Sodium Cyanide
Ammonium Benzoate	Calcium Citrate	Ferrous Potassium Oxalate	Potassium Aluminum Silicate	Sodium Dichromate
Ammonium Chloride	Calcium Hydroxide	Ferrous Sulfate	Potassium Arsenate	Sodium Ferrcyanade
Ammomium Chlorostannate	Calcium Hypochlorite	Ferrous Thiocyanate	Potassium Arsenate Acid	Sodium Fluoride
Ammonium Fluoride	Calcium Iodide	Ferrous Thiosulfate	Potassium Bicarbonate	Sodium Hypochlorite
Ammonium Hydroxide	Calcium Nitrate	Fluosilicic Acid	Potassium Borate	Potassium Nitrate
Ammonium Iodate	Calcium Nitrile	Fumaric Acid	Potassium Bromide	Sodium Phosphate
Ammonium Iodide	Calcium Oxychloride	Hydrobromic Acid	Potassium Carbonate	Sodium Silicate
Ammonium Nitrate	Calcium Phosphate	Hydrochloric Acid	Potassium Chloride	Sodium Sulphate
Ammonium Oxalate	Calcium Sulfate	Hydrofluoric Acid	Potassium Cyanate	Sodium Sulfite
Ammonium Phosphate	Calcium Thiosulfate	Hydrogen Sulfide	Potassium Cyanide	Sodium Tetraborate
Ammonium Silicate	Carbon Disulfide	Hypochlorous Acid	Potassium Dichromate	Sodium Thiosulfate
Ammonium Sulfate	Carbonic Acid	Lauric Acid	Potassium Fluoride	Stannic Chloride
Ammonium Sulfide	Chloroacetic Acid	Lead Acetate	Potassium Hydrosulfide	Stearic Acid
Ammonium Trichloride	Chromic Acid	Lead Persulfate	Potassium Hydroxide	Sulfamic Acid
Barium Bromide	Chromic Sulfate	Lithium Acetate	Potassium Hypochlorite	Sulfuric Acid
Barium Carbonate	Chromous Chloride	Lithium Nitrate	Potassium Hypophosphite	Sulfurous Acid
Barium Chlorate	Chromous Iodide	Lithium Sulfide	Potassium Iodide	Tannic Acid
Barium Chloride	Citric Acid	Magnesium Acetate	Potassium Nitrate	Tantalum Fluoride
Barium Citrate	Copper Chloride	Magnesium Bromide	Potassium Phosphate	Tartaric Acid
Barium Dichromate	Copper Fluoride	Magnesium Carbonate	Potassium Phosphite	Titanium Chloride
Barium Hydroxide	Copper Nitrate	Magnesium Chloride	Potassium Silicate	Titanium Fluoride
Barium Iodate	Copper Sulfate	Magnesium Hydroxide	Potassium Sulfate	Titanium Nitrate
Barium Iodide	Cupric Bromate	Magnesium Nitrate	Potassium Sulfide	Titanium Tetrachloride
Barium Nitrate	Cupric Bromide	Magnesium Perchlorate	Potassium Sulfite	Zinc Chloride
Barium Nitrile	Cuprous Sulfate	Magnesium Sulfate	Potassium Thiocarbonate	Zinc Sulfate
Barium Oxalate	Cuprous Sulfite	Magnesium Thiosulfate	Potassium Thiocyanate	Zinc Fluosilicate
Barium Sulfate	Cuprous Thiocyanate	Maleic Acid	Rhodium Chloride	Zinc Formate
Barium Sulfide	Ferric Bromide	Manganese Chloride	Rhodium Sulfate	Zinc Permanganate

Below is a description of those common processes used throughout this and other industries.

Direct Reactions
Many inorganic products are produced via the reaction of an ore or salt with an acid or base, thus producing another salt. These reactors vary considerably from one to the other; from simple mixed vessels, to elaborate continuous processes with critically controlled temperatures. Depending on the volumes produced as well as the raw materials economic to the area and the purity required in the end product, single end products may have significantly different manufacturing processes. Raw materials may be batched into the reactor or metered into a continuous process using the feedback.

Absorption
Gas absorption is an important method for reacting liquids with gasses. Two examples of this process include the manufacture of potassium bromide by bromine gas absorption, and potassium iodide by iodide gas absorption, both into potassium hydroxide. Towers similar to scrubbers are used to bring the liquid in close contact with the gas. Varying designs such as packed towers, plate, or simple spray columns are selected based on the pressure drop, corrosiveness of the materials, heat exchange requirements and reaction kinetics of the system. In nearly all cases, the "solvent" is fed at the top of the absorber while the gas enters from the bottom. The absorbed substance is carried out by the solvent and leaves behind a solution at the bottom. Subsequent processing for the salt often involves evaporation and crystallization.

Flow rates of the solvent and the gas are often controlled to insure a balance between the two chemicals. For temperature controlled reactions, flow rates and temperatures of the steam, hot water, or cooling water will also be monitors to insure optimum performance of the system.

Evaporation
Evaporation involves those processes where a volatile solvent is removed from a solution by vaporization. The evaporation process is used regularly to reduce the volume of a solution for economical packaging, shipping and storage. It is also used to obtain a product in its most useful form (i.e. salt from brine), to remove impurities or contaminants, and to concentrate waste for easier disposal.

The steam heated evaporator is one of the most common types. It is efficient for transferring large amounts of heat to the liquid being evaporated. Different types of evaporators include natural-circulation which utilize the density difference between the liquid and the vapor to circulate the liquid past the heating surface, forced circulation evaporators which are generally used for very large applications, and the film-type evaporators. The rising film or long-tube vertical evaporator is widely used and consists of a vertical shell and tube heat exchanger surmounted by a vapor-liquid separator.

Crystallization
Many products occurring naturally can be purified in many different ways. Crystallization provides a method of purification that is important for production of sodium chloride, sodium and ammonium sulfate, and sucrose. Although simple in principal, the process is often a complex simultaneous process of heat and mass transfer made more difficult by fluid and particle mechanics. Impurities can also significantly affect the process.

The simplest design of crystallizer is a simple unstirred tank. Addition of a stirrer helps produce smaller and more uniform crystals. More elaborate forms of crystallization such as spray crystallization or reaction crystallization have been developed to provide more efficient production of some specific chemicals.

Table 2
Compound	Method of Manufacture	Markets

Sodium Bromine NaBr)	Neutralizing Sodium Carbonate or hydroxide with hydrobromic acid followed by evaporation and crystallization	Photographic - used in the preparation of light sensitive silver bromide emulsions, and as a restrainer in developers Pharmaceutical -sedative, anticonvulsant

Sodium Nitrate (NaNO₃)	Mined in Chile	Agriculture - Fertilizer; corrects soil acidity. Industrial - used in the manufacture of explosives, glass, fiber glass, enamels and porcelain. Also used in the production of charcoal briquettes Food - preservative in curing meats.

Sodium Nitrite (NaNO₂)	Reaction of Nitrogen oxides in Alkali	Used in organic chemical manufacture. Used in rubber processing chemicals for accelerators, retardants and antioxidants. Used in metal treatment and finishing operations Curing and preserving agent in bacon, ham, etc.

Sodium sulfate (Na₂SO₄)	Mined; purified via crystallization	Used in paper-pulp manufacture, detergents and glass manufacture Source of acid for toilet-bowl cleaners, automotive radiator cleaners and pool and spa pH adjustment.

Limestone: CaCO₃, MgCO₃Calcium Carbonate and Magnesium Carbonate	Mined in open pit quarries, blasted or crushed to produce smaller stones Cleaned via washing, scrubbing or flotation	Construction applications (concrete, cement, asphalt filler). Agricultural (liming soils, fertilizer filler), iron and steel metallurgy, water and waste treatment, chemical manufacture

Potassium Acetate	Potassium carbonate & acetic acid	Glass mfg. Softening agent for paper/textile

Potassium Bromide	Bromine Absorption	Photography, engraving, medicinal sedative

Potassium Carbonate	Carbonation of Potassium Hydroxide	Chocolate production, television glass, ceramics

Potassium Iodide	Absorption of iodine in potassium hydroxide	Animal and human food, pharmaceuticals, photography

Potassium Phosphate	Potassium carbonate & Phosphoric acid	Liquid detergents
	Potassium carbonate & Phosphoric acid	Liquid detergents

Calcium Chloride	Evaporation of underground brines	Deicing, dust control, road stabilization, concrete

Calcium Sulfate (Anhydrate) (Dihydrate - Gypsum) (Hemihydrate - Plaster of paris)	Mined primarily as Gypsum, converted to hemihydrate by heating	Construction, portland cement, agriculture

Aluminum Sulfate	Reaction of Bauxite with sulfuric acid (Bauxite: 40-60% AI₂0₃ - Aluminum)	Medicine, dyeing, water purification, paper, sizing, skin dressing

Fluorine	electrolysis of anhydrous potassium biflouride	Manufacture of uranium hexafloride (used in separation and enrichment of Uranium 235)

Hydrogen Fluoride	Reaction of Fluorspar ore (CaF2) and sulfuric acid	Reagent for production of other fluorine compounds, aluminum production, semiconductor

Spray crystallization occurs when droplets are sprayed into a large chamber where they fall countercurrent to an up-flowing stream of hot air. Fertilizer chemicals such as ammonium nitrate are manufactured on a large scale using this technique. Reaction crystallization enables precipitation of a solid phase through the chemical interaction of gases or liquids in a reactor where mixing takes place. One example is the manufacture of sodium bicarbonate produced by contacting flue gases containing 10 to 20% carbon dioxide in countercurrent contact with brine in packed towers.

Generally, crystallizers may be classified into a number of general categories: batch or continuous; agitated or non-agitated, controlled or uncontrolled (super saturation control) and evaporating, cooling, vacuum, or reaction. The temperature-solubility relationship between the solute and solvent is the most important characteristic when determining the method of crystallization.

Signet Applications

Regardless of the type of reaction, there are many applications for Signet products in inorganic chemical processing. Inorganic chemistry contains most of the water soluble acids, bases and salts used in virtually all industries

Water Treatment
Deionized water is frequently used in the processing of the higher grade (higher purity) products. Signet provides sensors and instruments that ensure proper system operation. Click here for more information on deionization systems.

Batch Control and Chemical Injection
The end product of carbonic acid, sodium bicarbonate, or sodium carbonate is completely pH dependent when CO 2 is dissolved into water. Other similar relationships are also common throughout the inorganic chemistry spectrum. Methods to manufacture these end products include batch processes or injecting chemicals during the process. See Batch Control & Chemical Injection.

Waste Water Neutralization
With a large amount of acids and bases used in inorganic processing, waste treatment is essential. If metals are present in any of the raw materials, heavy metal precipitation will also be found in the waste treatment areas of these plants. See Industrial Wastewater-Neutralization.

Industrial Waste Water Treatment
Final effluent monitoring may be required for plants to track their discharge volume and pH levels before releasing into lakes, streams, riverbeds, or city sewers. See Industrial Wastewater Treatment.

Scrubbers
Since fumes are also common with the acids and bases, scrubbers are also common. pH control of sodium hydroxide is frequently used to help absorb and neutralize acid fumes. See Fume Scrubbers