Chrome ore extraction for refining

Chrome ore extraction

Chrome ore extraction process is used to extract Chromium commercially from chromite (chromium oxide), which is found naturally.

Extraction and refining High-carbon ferrochromium :

Most ores smelted with coke in an electric furnace produce metals that are saturated with carbon. For ferrochromium, the saturation point is approximately 9 percent, but actual carbon content varies with the condition of the ore and the composition of the slag. For example, with a lumpy, refractory ore and a slag containing approximately equal amounts of magnesia, alumina, and silica, a ferrochromium is produced that contains 4 to 6 percent carbon and less than 1.5 percent silicon. This is a result of high temperatures generated by a viscous slag, of a slowly reacting bulky ore, and, possibly, of refining of the molten metal by undissolved ore in the slag. When the rate of the reducing reaction is increased by using fine ore, or when the slag is made less viscous by adding lime to the melt, the carbon level of the ferrochromium approaches saturation. Adding more silica to the charge produces what is called charge ferrochromium, a carbon-saturated alloy with an increased silicon content.

Some South African ores produce charge ferrochromium containing 52–54 percent chromium, 6–7 percent carbon, and 2–4 percent silicon; ores from Zimbabwe with a higher chromium-iron ratio yield a product that is 63–67 percent chromium, 5–7 percent carbon, and 3–6 percent silicon. During the smelting of high-carbon or charge ferrochromium, slag and metal are tapped from the furnace into a ladle and separated by decanting or skimming. The recovery of chromium from the ore varies: in a good operation 90 percent is recovered in the molten metal; of the 10 percent remaining in the slag, some is in metallic form and can be recovered by mineral processing techniques. The smelting of charge ferrochromium consumes 4,000 kilowatt-hours of electric power per ton of alloy produced, compared with 4,600 kilowatt-hours per ton for high-carbon ferrochromium.

Low-carbon ferrochromium - Extraction and refining

When chromite and lime are melted in an open electric-arc furnace and then contacted with ferrochrome silicon, a low-carbon (0.05 percent) ferrochromium can be obtained. In an alternate process, high-carbon ferrochromium is oxidized and then blended with additional high-carbon ferrochromium. The briquetted mixture is placed in a large vacuum furnace, which is heated by graphite resistors to 1,400° C (2,550° F) at a reduced pressure of 30 pascals. The carbon is removed from the alloy (going off as carbon monoxide) to a level as low as 0.01 percent.

The major impact on the land use during the pre-mining phase is removal of vegetation and resettlement of displaced population. During mining and post-mining phases, drastic changes in landscape with landform take place. The major associated impacts are soil-erosion, loss of top soil, creation of waste dumps and voids, disposal of wastes, deforestation etc. These impacts of iron ore mining on land can be minimized by careful planning the surface layout of the mining areas and by integrating the environmental aspects of each and every unit operation of mining activity. Another important aspect of the land management is the planning and design of the land reclamation programme right from the inception, including the development of the post mining land use planning for optimum utilisation of land in an efficient manner and for overall improvement in environmental scenario.

Chrome ore plant machine

SBM is a famous construction and mining equipments manufacturer in China, and offer types of machines for chrome ore extraction and refining plant, like crusher, grinding and washing machine. SBM also design chrom ore processing flow chart for chrome mine plant in South Africa, India, Kazakhstan, Zimbabwe, Finland, Iran, Brazil, USA, China, Oman, Pakistan, the Sudan, Malaysia, Turkey, Mozambique, Madagascar, Albania, Turkey, Philippines and New Caledonia.

Chrome ore mining

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