Pyrometallurgical refining process

Iron, copper, arsenic, and antimony can be readily removed by the above pyrometallurgical processes or variations of these (3). However, for the removal of large quantities of lead or bismuth, either separately or together, conventional electrolysis or anewly developed vacuum-refining process is used. The latter is now in use in Australia, Bolivia, Mexico, and the CIS (5). 

The conventional smelting and refining process for copper, nickel, lead and zinc sulfide ores result in the evolution of a large amount of sulfu dioxide gas which in most instances is released to the atmosphere. Ther have b( en attempts to recover part of the sulfur as sulfuric acid or in som form (HI, H4, H5) at various stages of the pyrometallurgical processing... 

The recycling process for steel was described in Sect. 2. Some elements, which are called the tramp elements, caimot be removed from molten iron with present pyrometallurgical refining methods. The tramp elements and the influence of them on the mechanical properties and workability of steel are listed in Table 6. Copper content in scrap is 0.1-0.5 mass%. Measures to prevent copper from mixing... 

Lead ores, except those from the Mississippi Valley, are an important source of silver. Silver is collected in the crude lead and removed in the refining process, as also are other metals such as copper, arsenic, antimony, bismuth, zinc, cadmium, nickel, tin, gold and platinum. The refining of lead is complex and a number of processes and techniques are involved. There are two methodologies utilized one is electrolysis, in which the crude lead is anodicaUy dissolved and precipitated on cathodes the other is pyrometallurgical, including cupellation or distillation processes. Lead is sold as refined lead with a purity of99.99%. 

Pyrometallurgical smelting processes produce lead bullion which must be refined to remove a range of impurities derived from ore, fluxes and... 

Pyrometallurgical refining involves the removal of dissolved impurities in a sequence of steps, where different reagents are added to the molten lead in a strictly controlled manner using several kettles or refining vessels. In the process a number of drosses are produced, which are mechanically removed and treated. A typical sequence of stages would be as follows (see Fig. 5-3) ... 

Process modifications in recent years have included the automation of several of the treatment stages, increases in the scale of refining vessels, improved by-product recoveries and more efficient enviroiunental controls. Research is also focusing on the further development of continuous pyrometallurgical refining systems which will raise efficiency and reduce environmental emissions. 

Preparation. Sulphides are readily converted to oxide by roasting in air, that remove all sulphur as S02 this pre-treatment is followed by pyrometallurgical process by heating with carbon, or electrolytic process to obtain zinc. It is also possible by controlled oxidation to convert ZnS to the water soluble ZnS04, which can be extracted and electrolyzed to produce zinc. Crude zinc obtained by pyrometallurgical process can be refined by distillation taking into account the comparatively low boiling temperature of zinc. 

Sulfide ores are processed by a number of pyrometallurgical processes roasting, smelting, and converting. During these processes, sulfur and iron are removed to deld a sulfur-deficient copper-nickel matte. Especially after roasting and converting, the nickel in the matte may consist primarily of nickel subsulfide. After physical separation of the copper and nickel sulfides, the nickel is refined electrochemically or by the carbonyl process. The treatment of the matte depends on the end use of the nickel. Alternatively, the sulfide can be roasted to form a nickel oxide sinter that is used directly in steel production. 

Wet chemical, or hydrometallurgical processes for battery recycling differ fundamentally from pyrometallurgical approaches in that they aim to produce finished products with a high resale value rather than lower value material, which is further refined or used in a separate industry. This quest for greater added value is often borne out of necessity, to cover the high capital investment and operating costs. 

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