Metal basic sulfates

In the initial thiocyanate-complex Hquid—Hquid extraction process (42,43), the thiocyanate complexes of hafnium and zirconium were extracted with ether from a dilute sulfuric acid solution of zirconium and hafnium to obtain hafnium. This process was modified in 1949—1950 by an Oak Ridge team and is stiH used in the United States. A solution of thiocyanic acid in methyl isobutyl ketone (MIBK) is used to extract hafnium preferentially from a concentrated zirconium—hafnium oxide chloride solution which also contains thiocyanic acid. The separated metals are recovered by precipitation as basic zirconium sulfate and hydrous hafnium oxide, respectively, and calcined to the oxide (44,45). This process is used by Teledyne Wah Chang Albany Corporation and Western Zirconium Division of Westinghouse, and was used by Carbomndum Metals Company, Reactive Metals Inc., AMAX Specialty Metals, Toyo Zirconium in Japan, and Pechiney Ugine Kuhlmann in France. 

Mercury(ll) sulfate hydrolyzes in water forming a basic sulfate HgS04 2Hg0. It forms double sulfates with alkali metal sulfates, such as K2S04-3HgS04-2H20. 

Mention has already been made of the uciion of oxygen and oxidants on metal. It should be noted that metals react with sulfides, such as hydrogen sulfide, and are subsequently subject to additional slow attack by oxygen and oxidants. Thus, copper reacts to form sulfide and then the basic copper sulfate. 

Chromium metal is commercially produced in the United States by the reduction of chromite ore with carbon, aluminum, or silicon, and subsequent purification. Sodium chromate and dichromate are produced by roasting chromite ore with soda ash. Most other chromium compounds are produced from sodium chromate and dichromate (Hartford 1979 Westbrook 1979). For example, basic chromic sulfate (Cr(0H)S04), commonly used in tanning, is commercially produced by the reduction of sodium dichromate with organic compounds (e.g., molasses) in the presence of sulfuric acid or by the reduction of dichromate with sulfur dioxide. Lead chromate, commonly used as a pigment, is produced by the reaction of sodium chromate with lead nitrate or by reaction of lead monoxide with chromic acid solution (IARC 1990). 

Butlerite-type chain. Open-framework metal sulfates form the [M(T04)[Pg.371]

Sulfur oxides (S02 and S03) present in flue gases from upstream combustion operations adsorb onto the catalyst surface and in many cases form inactive metal sulfates. It is the presence of sulfur compounds in petroleum-based fuels that prevent the super-sensitive base metal catalysts (i.e., Cu, Ni, Co, etc.) from being used as the primary catalytic components for many environmental applications. Precious metals are inhibited by sulfur and lose some activity but usually reach a lower but steady state activity. Furthermore the precious metals are reversibly poisoned by sulfur compounds and can be regenerated simply by removing the poison from the gas stream. Heavy metals such as Pb, Hg, As, etc. alloy with precious metals and permanently deactivate them. Basic compounds such as NH3 can deactivate an acidic catalyst such as a zeolite by adsorbing and neutralizing the acid sites. 

Although copper is not highly reactive (it will not reduce H+ to H2, for example), this reddish colored metal does slowly corrode in air, producing the characteristic green patina consisting of basic copper sulfate,... 

Other investigators (14, T3) contend that the bacteria biologically oxidize the ferrous to the ferric state as sulfate, which in turn attacks the metal sulfides ores, resulting in both the dissolution of the metal and the oxidation of the sulfide. In the process the ferric iron reduces back to the ferrous state. An increase in the pH causes the basic ferric sulfate to precipitate (self-buffering action) with corresponding release of sulfuric acid. This has the cumulative effect of increasing the acidity of the mine water. 

The nickel in solution in the slurry is completely precipitated without liquids-solids separation with metallic powered iron at about 150°C under a pressure of 150 psig. The precipitated nickel contains occluded basic ferric sulfates which are decomposed by calcining at 950°C to produce a mixture of metallic nickel, metallic iron, and iron oxides. Melting of this mixture with a slag is calculated to yield a ferro-nickel containing more than 55% nickel. 

The variety of substances used as additives in polymers is considerable. For example, the fillers may include china clay, various forms of calcium carbonate, talc, silicas (diatomaceous silica), silicates, carbon black, etc. The impact modifiers typically include other polymers. Plasticizers include certain polymers with low (oligomers), dialkyl phthalates, dialkyl sebacates, chlorinated paraffin waxes, liquid paraffinic fractions, oil extracts, etc. Heat stabilizers include heavy metals salts such as basic lead carbonate, basic lead sulfate, dibasic lead phosphite (also acting as a light stabilizer), dibasic lead phthalate, stearates, ricinoleates, palmitates and octanoates of cadmium and barium, epoxide resins and oils, amines, diphenylurea, 2-phenylindole, aminocrotonates. The antioxidants include tris-nonyl phenyl phosphite, 2,6-di-ferf-butyl-p-cresol (BHT), octadecyl-3,5-di-terf-butyl-4-hydroxyhydrocinnamate, etc. The UV stabilizers include modified benzophenones and benzotriazoles. Processing lubricants include calcium stearate, stearic acid, lead stearate, various wax derivatives, glyceryl esters and long-chain acids. Fire retardants include antimony oxide, some pyrophosphates, etc. 

The SO additives are formed by an oxide function, usually Ce203, which can rapidly oxidize SO2 to SO3. This then reacts with a more basic oxide, such as MgO or MgO-A1203, also present in the additive, and forms the corresponding metal sulfate. All these processes occur in the regenerator unit. Then, when the additive is passed to the reactor, it reacts with H2 to either be regenerated, forming H2S and H2O, or to form a sulfide and H2O. The sulfide can then be hydrolyzed in the stripper to form H2S. The different reactions occurring are schematized in fig. 9. 

Since metal sulfates do not change the color of the basic indicators having pK = —5.6 or —8.2, their acid strengths are relatively low compared to those of silica-alumina pK — 8.2), natural clays... 

The selectivity of the metal sulfate catalyst is influenced by many factors besides its acidic property, such as geometric structure involving a pore structure, arrangement of basic sites, polarity of the surface, etc. For example, the relative values of the first-order rate constants (per imit acidity at pK — 3) of the depolymerization catalyzed by nickel sulfate, cupric sulfate, and silica-alumina were found to be 1100 300 1. The difference may be attributed to the differences in acid-base bi-functional catalysis of these catalysts. This view may be said to have originated in 1948 when Turkevich and Smith (45) showed that the isomerization of 1-butene to 2-butene is catalyzed by metal sulfates, sulfuric acid, phosphoric acid, etc., but little by acetic acid, hydrogen chloride, etc. The high catalytic activity of the catalysts of the former group is considered as due to acid-base bifunctional catalysis as illustrated by Fig. 14. Independently, Horiuti (45a) advanced the same idea... 

Aqua regia is an effective solvent for most base metal sulfates, sulfides, oxides, and carbonates. Some elements, however, form very stable diatomic oxides, referred to as refractory species. Aqua regia provides only a partial digestion for most rock-forming and refractory elements. Hydrofluoric acid can destroy silicate matrices completely to liberate trapped trace constituents. Basic solutions can dissolve tissue and many anionic forms of inorganic ions. Complex-ing solutions such as EDTA are used under conditions that dissolve specific ions (Perrin 1964). 

By oxidation of the metal beneath a highly basic molten sulfate film, ions are generated at the oxide/melt interface by reduction of O2 or of the sulfate ion ... 

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