Sulphation roasting

The scheme F involves sulphating roasting. The conditions are so chosen that iron is converted to its oxidic form (Fe203) while nickel and copper are converted to nickel sulfate and copper sulfate respectively. The product is subsequently water leached to take the sulfates into solution, leaving the iron oxide in the leach residue. 

COBALT RECOVERY THROUGH SULPHATING ROAST OF CU/CO CONCENTRATE OF KATANGA MINING... 

Historically, the cobalt selective sulphating roast temperature has been in the 650 to 725°C range [2, 3]. Figure 1 shows the cobalt-oxygen-sulphur equilibrium at 700°C, for different oxygen levels (provided in fluidizing air) and sulphur dioxide (product of roasting) partial pressures, as predicted by the commercial software HSC . 

At the optimum conditions set by the cobalt selective sulphating roast, for example at 700°C, the copper recovery as sulphate is not complete, and inevitably results in some sulphur dioxide release. Figure 2 shows the copper-oxygen-sulphur equilibrium at 700°C, for different oxygen levels and sulphur dioxide partial pressures. 

Considering the minimum temperature of proven sulphating roast (600°C), the predominance diagram for Mg-O-C shows that substantial extent of calcination and MgO formation can be expected. 

Theys, L.F. and Lee, L.V. (1958) Sulphate Roasting Copper-Cobalt Sulphide Concentrates Journal of Metals 134-136. 

Cobalt Recovery through Sulphating Roast of Cu/Co Concentrate... 

Lead The production of lead from lead sulphide minerals, principally galena, PbS, is considerably more complicated than the production of zinc because tire roasting of the sulphide to prepare the oxide for reduction produces PbO which is a relatively volatile oxide, and therefore the temperature of roasting is limited. The products of roasting also contain unoxidized galena as well as die oxide, some lead basic sulphate, and impurities such as zinc, iron, arsenic and antimony. 

Preparation. Industrially, cobalt is normally produced as a by-product from the production of copper, nickel and lead. The ore is roasted to form a mixture of metals and metal oxides. Treatment with sulphuric acid leaves metallic copper as a residue and dissolves out iron, cobalt and nickel as the sulphates. Iron is separated by precipitation with lime (CaO) while cobalt is produced as the hydroxide by precipitation with sodium hypochlorite. The trihydroxide Co(OH)3 is heated to form the oxide and then reduced with carbon (as charcoal) to form cobalt metal. 

Potassium iodide can also be obtained from the aq. extract of kelp or from the mother liquid remaining after the separation of sodium chloride and potassium sulphate from sea-water by evaporation. In E. Allary and J. Pellieux process,8 the liquid is evaporated to dryness and roasted in a special furnace so as to avoid a loss of iodine. The product is fractionally extracted with cold water, when a soln. is obtained which on evaporation gives a residue with 50 per cent, of alkali iodide. This product is extracted.in a special digester with 50 per cent, alcohol. The solvent dissolves little more than the iodides. The alcohol is distilled off, and on evaporation a residue containing about 34 per cent, of potassium iodide, and 66 per cent, of sodium iodide is obtained. To convert the latter into potassium iodide, the proper quantity of a soln. of potassium carbonate is added and carbon dioxide passed into the liquid whereby sodium bicarbonate is precipitated. The precipitate is separated by a filter press, and the small amount of sodium bicarbonate remaining in the soln. is separated by the addition of a little hydrochloric acid and the sodium chloride and potassium iodide separated by fractional crystallization. In E. Sonstadt s process, the mother liquid is treated with chlorine mixed with potassium chlorate or permanganate so as to convert the iodine into iodate. A soln. of a barium salt is added, and the barium iodate treated with potassium sulphate. Barium sulphate is precipitated, and the soln. of potassium iodate is evaporated to dryness and calcined to convert the iodate to iodide. The latter is purified by crystallization. 

Thermal Stability of Sulphates. 1. Put 1-2 g of sodium bisulphate into a small porcelain bowl or crucible. First carefully heat it, and then strongly roast it. What compounds form Write the equations of the reactions. 

Put several iron II) sulphate crystals on the lid of a porcelain crucible, heat them, and then strongly roast them. Hold litmus paper wetted with water over the crystals. What happens Write the equation of the reaction. 

Processing of Barium Sulphate into Barium Chloride, a. Preparation of Barium Sulphide. Mix 4 g of barium sulphate and 2 g of powdered charcoal, place the mixture into a chamotte or porcelain crucible, and cover the mixture with powdered charcoal. Close the crucible with its lid and roast it strongly (600-700 °C) for an hour in a muffle furnace. Write the equation of the reaction. 

Preparation of Aluminium Sulphate from Kaolin. Roast about 25 g of kaolin with the access of air in a muffle furnace (800 °C) to remove the moisture and oxidize... 

The principal objection to this method of assay is the largo amount of lead which is produced for cupellation, since pure iron pyrites affords, when thus treated, eight and a half partB of lead, whilst sulphate-of antimony and grey copper ore yield from six to seven parts. This inconvenience, as well as the trouble of roasting, may be avoided by the cautious and gradual addition of nitrate of potassa, which effects the partial oxidation of the mineral, and enables tho skilful assayer to pro-... 

Japan ink is made as other inks, but the sulphate of iron is oxidised by roasting. This ink. Is intensely black when written with, but tlio color does not retain its depth or lustre. Besides these disadvantages, it... 

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