Calcium production methods

Electrolysis. Although in Western countries the aluminothermic process has now completely replaced the electrolytic method, electrolysis is beheved to be the method used for calcium production in the People s RepubHc of China and the Commonwealth of Independent States (CIS). This process likely involves the production of a calcium—copper alloy, which is then redistilled to give calcium metal. 

Reduction of potassium fluoride with calcium carbide at 1,000 to 1,100°C (Greisheim process) is an effective production method (Greer, J.S., Madaus, J.H and J.W. MausteUer. 1982. In Kirk-Othmer Encyclopedia of Chemical Technology, 3 ed. p. 914, New York Wiley Interscience) ... 

Industrial citric acid production began in 1860 and for the next 60 years was dominated by Italian producers. The original production method was based on extraction from the juice of citrus fruits by adding calcium oxide (CaO) to form calcium citrate, Ca3(C6H507)2, as an insoluble precipitate that can then be collected by filtration. Citric acid can be recovered from... 

An industrially important method of manufacturing chlorine dioxide is the decomposition of calcium chlorate by hydrochloric acid (see later Mathieson production method). 

ABSTRACT Calcium-enriched bio-oil (CEB) can be used for flue gas desulfurisation in coal and waste combustion chambers. It is produced by mixing biomass derived fast pyrolysis oil with calcium oxide. The aim of the proposed project is to develop a technology i) to produce calcium-enriched bio-oil with a calcium content of 13 wt,%, and ii) to test the CEB in a combustion chamber by co-firing it with a sufur-containing fuel. In this paper the production method of CEB will be elucidated, and small-scale experiments related to CEB spraying will be presented. Finally, co-combustion experiments of a sulfur-containing fuel with CEB in a small flame tunnel (20 kW, ) will be reported. 

Ostberg T, Graffner C. Calcium alginate matrices for oral multiple unit administration. Part 1. Pilot investigations of production method. Acta Pharm Nord 1992 4(4) 201-208. 

Dictyostelium discoideum cells can be transformed with plasmid DNA by convenient methods. The first attempts at this, using the calcium phosphate method, were reported in the early 1980s [17, 18]. Protocols were subsequently optimized by Firtel and coworkers [19, 20] and modified in many laboratories (e.g. Ref [21]). Up to 2000 transformants can be recovered from 10 D. discoideum cells [20], with electroporation protocols having been reported [22, 23]. It has also been noted that the choice of transformation method can strongly influence the yield of heterolo-gously expressed proteins [24]. Hence, both calcium co-precipitation and electroporation should be compared to generate optimized expression strains for the production of biopharmaceutical proteins in D. discoideum. 

This salt is isolated by filtration in the final step, washed with water and acidified with sulfuric acid to liberate free lactic acid with formation of calcium sulfate as solids. When ammonia is used for the neutralization, the ammonium lactate is formed and directly converted into butyl lactate by esterification with n-butanol, as shown in Scheme 1.2. Here, the ammonia is recovered and recycled. The following distillation and hydrolysis of butyl lactate gives an aqueous lactic acid with high efficiency. The lactic acid obtained by this method has higher purity than that obtained by the calcium salt method. The technologies for the above lactic acid fermentation and purification have well been established, and the production of both D- and L-lactic acids is conducted industrially in a plant scale of 100000 ton year. ... 

Method 2. Transfer the dark-coloured reaction product to a separatory funnel and shake successively with water, with sufficient 5-10 per cent, sodium hydroxide solution to ensure that the washings are alkaline to litmus, and finally with water. Dry with anhydrous magnesium sulphate or calcium chloride. Filter through a fluted filter paper into a small distilling flask and distil slowly. Collect the crude bromobenzene at 150-170° pour the residue whilst still hot into a small porcelain basin. Redistil the hquid of b.p. 150-170° (3) and collect the bromobenzene at 154-157° the yield is about 60 g. 

The method of obtaining aluminum metal by the electrolysis of alumina dissolved in cryolite was discovered in 1886 by Hall in the U.S. and at about the same time by Heroult in France. Cryolite, a natural ore found in Greenland, is no longer widely used in commercial production, but has been replaced by an artificial mixture of sodium, aluminum, and calcium fluorides. 

Another difficulty in this reaction lies in the preparation of pure chloroacetaldehyde. The low yield observed is due to simultaneous formation of by-products (polyhalogenation). So vinylchloride was used as a starting material for this synthesis (449). A simpler method is to react chlorine with vinylchloride in aqueous solution and then to dehydrate the semihydrated chloroacetaldehyde by distillation through a column of calcium chloride heated to 70 to 90 C (451). 

Normally, a slight excess of sulfuric acid is used to bring the reaction to completion. There are, of course, many side reactions involving siHca and other impurity minerals in the rock. Fluorine—silica reactions are especially important as these affect the nature of the calcium sulfate by-product and of fluorine recovery methods. Thermodynamic and kinetic details of the chemistry have been described (34). 

Opa.nte. There are two methods used at various plants in Russia for loparite concentrate processing (12). The chlorination technique is carried out using gaseous chlorine at 800°C in the presence of carbon. The volatile chlorides are then separated from the calcium—sodium—rare-earth fused chloride, and the resultant cake dissolved in water. Alternatively, sulfuric acid digestion may be carried out using 85% sulfuric acid at 150—200°C in the presence of ammonium sulfate. The ensuing product is leached with water, while the double sulfates of the rare earths remain in the residue. The titanium, tantalum, and niobium sulfates transfer into the solution. The residue is converted to rare-earth carbonate, and then dissolved into nitric acid. 

In the calendering method, a PVC compound which contains plasticizers (qv) (60—120 phr), pigments (qv) (0—10 phr), fillers (qv) (20—60 phr), stabilizers (10—30 phr), and other additives, is kneaded with calender roUs at 150—200°C, followed by extmsion between clearance-adjusted roUs for bonding onto the substrate. This method is employed for products with thick PVC layers, ie, of 0.05—0.75 mm thickness. The main plasticizer used is di-2-ethylhexyl phthalate (DOP). For filler to reduce cost, calcium carbonate is mainly used. A woven or knit fabric made of cotton, rayon, nylon, polyester, and their blend fiber is used as substrate. For foamed vinyl-coated fabrics, the bonded materials are heated in an oven to decompose the foam-blowing... 

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