Caustic soda refining

Miscella refining (Cavanagh, 1976) is a special case of continuous caustic soda refining. The most favourable conditions for the process are those of the solvent extraction plant where it is also desired to refine the oil and perhaps further process it by winterization. For this reason cottonseed is the oil most usually processed in this manner. The miscella from the extraction plant is evaporated to the desired oil hexane proportion, approximately 65 35 in the case of cottonseed oil. The corrected miscella is then pretreated with phosphoric acid, neutralized and the soapstock centrifugally separated as for the normal 100% oil process. Soapstock separation is very efficient and therefore the miscella does not need to be washed. The solvent is evaporated from the refined oil and the oil is bleached and deodorized. The process is capable of giving higher yields of refined oil and improved colour of the bleached oil by comparison with non-miscella refined oils. 

The quantity of activated earth required is dependent on the quality of the oil, the activity of the earth and the process conditions, and is normally between 0.2 and 2.0% of the weight of the oil. Apart from the cost of the earth and the oil retention on the spent earth, it is advisable to use as little earth as possible when bleaching caustic-soda-refined oils because of an increase in free fatty acid content in the oil which is... 

Aluminium is obtained on a large scale by the electrolysis of the oxide, dissolved in fused cryolite The oxide, occurring naturally as bauxite, AI2O3.2H2O, usually contains silica and iron(III) oxide as impurities. These must be removed first, since aluminium, once prepared, cannot be freed of other metals (which will be deposited on electrolysis) by refining it. The crude oxide is dissolved under pressure in caustic soda solution the aluminium oxide and silica dissolve and the ironflll) oxide is left ... 

Alkali Treatment. Caustic washing is the treatment of materials, usually products from petroleum refining, with solutions of caustic soda. The process consists of mixing a water solution of lye (sodium hydroxide or caustic soda) with a petroleum fraction. The treatment is carried out as soon as possible after the petroleum fraction is distilled, since contact with air forms free sulfur, which is corrosive and difficult to remove. The lye reacts either with any hydrogen sulfide present to form sodium sulfide, which is soluble in water, or with mercaptans, foUowed by oxidation, to form the less nocuous disulfides. 

Refining. The alloy of bismuth and lead from the separation procedures is treated with molten caustic soda to remove traces of such acidic elements as arsenic and teUutium (4). It is then subjected to the Parkes desilverization process to remove the silver and gold present. This process is also used to remove these elements from lead. 

The desilverized alloy now contains bismuth as well as lead and ziac. To remove the lead and ziac, advantage is taken of the fact that ziac and lead chlorides are formed before bismuth chloride [7787-60-2J, BiCl, when the alloy is treated at 500°C with chlorine gas. Ziac chloride [7646-85-7] ZnCl, forms first, and after its removal lead chloride [7758-95-4], PbCl2, forms preferentially. This process is continued until the desired level of lead removal has been reached. The bismuth is given a final oxidation with air and caustic soda the refined product has a purity of 99.999%. 

C. Sour water treating is found in natural gas processing, refining, and the substitute fuel processes. Cmmpounds present normally include a few to all those listed in A. 3. above. In addition, the water pH is normally controlled with caustic soda or other salt. In the past, processing has been near ambient temperatures and pressures. Future operations may, however, be at elevated temperatures and pressures. 

Wakbukton s method of effecting the purification of rape oil is by treatment with caustic alkali, ia which, the albuminous and other impurities are soluble, and are. separated, associated with soapy matters. In a suitable vessel, containing fifty-two parts of. caustic soda solution, of specific gravity 1-010, are to be put one hundred pounds of the refined oil those are to be stirred with a wooden ladle till well mixed. The mixture is then allowed to stand twenty-four hours undisturbed, in a cold place, after which it is then slowly warmed, and again well stirred. After twenty-four hours subsidence all the oil will have separated if such should not bo entirely the case, the complete separation may be effected by the addition of a small quantity of spirit of wine. The oil drawn off from the liquor is afterwards well washed with hot water, till the pure oil is obtained without taste or color, and if desired, may be passed through a filter. The soap which deposits may be used as an ordinary detergent... 

Mercury is mined predominantly as HgS in cinnabar ore and is then converted commercially to a variety of chemical forms. Key industrial and commercial applications of mercury are found in the electrolytic production of chlorine and caustic soda the manufacture of electrical equipment, thermometers, and other instruments paint and pigment production dental amalgam and gold refining. Use in pharmaceuticals and in biocides has declined substantially in recent years, but occasional use in antiseptics and folk medicines is still encountered. Environmental exposure to mercury from the burning of fossil fuels—or the bioaccumulation of methylmercury in fish—... 

Solvent extraction has found application for many years in the coal tar industry. Extraction of phenols from coal-tar distillates by washing with caustic soda solution can be considered such a process. In the isomer separation, a process for separation of m- and p-crcsol by dissociation extraction has been reported. Work is in progress in several parts of the world to use solvent extraction for the direct manufacture of chemicals from coal. Crude tall oil is a byproduct of pulp mills. It is refined by solvent extraction using propane or furfural. 

PVC is a product based on two of the earth s natural resources, salt and oil. Salt water electrolysis yields chlorine (in addition to caustic soda and hydrogen). Ethylene can be derived from naphtha when oil is refined. Chlorine and ethylene can be combined to form the monomer, vinyl chloride (VCM). PVC results from the polymerisation of vinyl chloride. 

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