In modern metallurgy, the copper and nickel used in the metallurgical furnace are composite electric furnace, an electric furnace used for smelting due to such ores and concentrates, it is also known iron furnace. The ore furnace has a higher furnace temperature and is therefore commonly used to treat ore containing more refractory gangue (calcined or pre-reduced chlorinated ore after drying).
(1) easy adjustment of the bath temperature, and can obtain a high temperature, refractory-containing material may be processed more raw material, the slag easily overheat, beneficial reduction of iron tetroxide, metal slag contains less price.
(2) The amount of furnace gas is small and the dust content is low. A complete electric furnace sealing facility can increase the concentration of sulfur dioxide in the flue gas and can be used.
(3) It has a large adaptability to the quality of materials, and can handle some miscellaneous materials and return materials.
(4) Easy to control, easy to operate, easy to mechanize and automate.
(5) a low gas temperature, the heat utilization rate of 45% - 60% and the top portion of the furnace wall can be built with inexpensive refractory clay brick.
Electric furnace smelting also has certain disadvantages:
(1) When the power consumption is large and the electricity cost is high, the production cost is high.
(2) The water content of the charge is strict (not higher than 3%).
(3) The desulfurization rate is low (16% to 20%). When processing materials with high sulfur content, pre-desulfurization must be baked before melting.
(I) Roasting of nickel sulphide concentrate Figure 1 shows a typical process of roasting-electric furnace smelting-converter blowing. When the concentrate has a high grade and low sulfur content, it can be directly smelted without roasting because the desulfurization rate of the electric furnace is low. When processing the low grade concentrate, it is necessary to remove some sulfur before roasting before smelting. The calcined sand is put into an electric furnace to produce a low nickel niobium with a Ni+Cu content of about 24%.
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The roasting of the sulphide industry can be carried out using a fluidized furnace or a rotary kiln, and the former employs more plants.
(1) Fluidized roasting of nickel sulfide concentrate. The general temperature is 600-700 °C. The oxidation of FeS to Fe 3 O4 and SO 2 is the main reaction in the calcination process. When conventional partial desulfurization roasting is carried out on nickel yellow iron or chalcopyrite concentrate, little or no NiO or Cu 2 O is formed. The fluidized roasting product can be discussed using the Ni-S-O system and the Fe-S-O system state diagram at 650 °C as shown in FIG. As shown in the figure, several dominant zones under calcination conditions are stable zones of Fe 3 O 4 , FeS and NiS, respectively.
The air/concentrate ratio produced by the fluidized roaster is controlled to a stoichiometric requirement close to the optimum degree of roasting, and the oxygen utilization rate is close to 100%. Generally, the amount of O 2 in the flue gas is <1% (volume), which is beneficial to avoid the formation of metal sulfur complex salt in the flue gas dust collection system. The process flow of nickel sulfide concentrate roasting is shown in Figure 3.
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