Process for enhanced pre-reduction of chromite
A technology for chromite and ferrochromite, applied in the field of partial oxidation of unagglomerated chromite, can solve the problems of chromite ore agglomerate deterioration, pollution of ferrochromite, and infrequent use of additives, etc.
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Embodiment 1
[0131] Embodiment 1: Experimental data shows that by adopting the method of the present invention to enhance (improve) chromite pre-reduction
[0132] Basic plan
[0133] Grinding consists of 20.0% by weight of anthracite (fixed carbon content of 75%), 3.5% by weight of attapulgite clay and the balance of South African metallurgical grade chromite ore (Cr 2 o 3 content of 45%), such that the mixture contains particles, wherein 90% of such particles are smaller than 75 microns (process step 1, figure 1 ).
[0134] The ground mixture was then granulated in a similar manner to that described by Kleyhans et al. (2012) (process step 2, figure 1 ). The granulation method ensures that the density, shape and size of the agglomerates remain consistent, enabling univariate studies of other process parameters.
[0135] The pre-reduction of the obtained green pellets (solid-state reduction of chromite) is carried out in a tube furnace (process step 3, figure 1 ). Similar to Kleyhan...
Embodiment 2
[0147] Example 2: Using additives in combination with preoxidation to enhance prereduction
[0148] As mentioned previously, additives have been proposed to enhance chromite pre-reduction (solid-state reduction of chromite), including but not limited to CaCO 3 , NaCl, CaF 2 , NaF-CaF 2 、Na 2 B 4 o 7 , NaF, Na 2 CO 3 , CaB 4o 7 , B 2 o 3 , CaCl, SiO 2 、Al 2 o 3 、K 2 CO 3 、Na 2 o 2 , CaO, MgO, Fe, Cr and K 2 O.
[0149] In this regard, the inventors investigated the use of CaCO 3 as an additive. Select CaCO 3 , because CaCO 3 Usually added as a flux to currently used smelting methods operating on alkaline slags (process step 7, figure 1 ). In this way, CaCO 3 Does not constitute addition to the smelting step (process step 7, figure 1 ) in foreign matter.
[0150] To test for CaCO 3 As the effect of the additive on the pre-reduction of chromite, a test similar to that described for the basic scheme in Example 1 was carried out. The only difference is ...
Embodiment 3
[0154] Example 3: Pre-oxidation of chromite ore in the presence of additives and its effect on pre-reduction
[0155] In order to test that before pre-reduction (solid-state reduction of chromite) in CaCO 3 To determine the effect of preoxidizing chromite ore in the presence of chromite, an experiment similar to that described in Example 1 was carried out. The only difference is the pre-oxidation of the ore in CaCO 3 in the presence of additives. As mentioned above, since the temperature of 1000° C. has been determined as the optimum pre-oxidation temperature ( figure 2 ), so at this temperature at different wt% additions of CaCO 3 The pre-oxidation of the chromite ore is carried out in the presence of . It is to be understood that this experimental procedure differs from the prior art experimental procedure using an additive to improve chromite pre-reduction (Example 2), where the additive is typically added in process step 1 ( figure 1 ) or in process step 2 ( figure ...
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