The invention relates to a method for recycling vanadium-chromium resources, belonging to the field of resource recycling. The invention aims at providing a method for recycling vanadium-chromium resources. The method for recycling vanadium-chromium resources comprises the following steps: a. mixing vanadium-chromium slag with calcium carbonate to obtain a primary mixture material, and oxidizing-roasting the primary mixture material to obtain a primary roasting clinker; b. performing acid leaching to the primary roasting clinker to obtain acid leaching liquor and acid leaching slag; c. drying acid leaching slag, grinding and mixing together with sodium carbonate to obtain a secondary mixture material, oxidizing-roasting the secondary mixture material to obtain secondary roasting clinker; d. performing water leaching to the secondary roasting clinker, to obtain water leaching liquor and water leaching slag; and e. respectively separating and extracting vanadium, chromium and iron from the acid leaching liquor, water leaching liquor and water leaching slag. The method for recycling vanadium-chromium resources has the advantages of being high in vanadium and chromium recycling rate, simple in technology, low in equipment requirement, less in environmental pollution and the like.

Method for recycling vanadium-chromium resources

Two-stage roasting method for chromite

The invention discloses a method for calcium-free calcination production of sodium chromate and chromium-containing cast iron as a co-product. The method comprises the following steps of 1, first-stage calcination by mixing chromite and soda ash according to a certain ratio to obtain a first-stage mixed material, wherein a soda ash use amount is 35-60% of the theoretical alkali use amount, putting the first-stage mixed material into a rotary kiln, carrying out oxidizing calcination, and carrying out impregnation and filtration of the calcined clinker to obtain a first-stage sodium chromate alkali solution and filter residues, and 2, treating the filter residues, and carrying out second-stage calcination and third-stage calcination of the filter residues by the step 1 to obtain second-stage calcination filter residues, third-stage calcination filter residues, a second-stage calcination sodium chromate alkali solution and a third-stage calcination sodium chromate alkali solution, wherein the third-stage calcination filter residues can be used for co-production of chromium-containing cast iron. The method does not adopt any auxiliary materials in calcination, and effectively avoids ring forming of the rotary furnace. The calcination residues obtained by the method does not contain hexavalent chromium compounds and thus chromium residue harmlessness and recycling are realized. Through co-production of high-carbon chromium iron, a chromium comprehensive use ratio is improved by more than 95%. Through smelting, produced electroslag does not contain hexavalent chromium so that thorough detoxification of chromium residues is realized.

Method for calcium-free calcination production of sodium chromate and chromium-containing cast iron as co-product

The invention discloses a method for preparing chromium salt. The method is characterized by comprising the following steps: sufficiently and uniformly mixing a raw material containing chromium oxide (chrome ore or chromium slag) with sodium carbonate, carrying out oxidizing roasting at the roasting temperature of 900-1100 DEG C for 0.5-2.5 hours in an atmosphere with the oxygen content of higher than 20% by using microwaves as a heat source, leaching the roasted product with water, and preparing chromium salt from the leach solution. The chemical analysis on the clinker and leaching slag indicates that the insoluble waste slag contains less than 5% of chromium (on the basis of chromic oxide). The method reduces the chromium content in the discharged chromium slag, enhances the chromium utilization ratio in the chromium salt production process, effectively saves the chrome ore resources, and has obvious advantages of resource saving and environmental protection by using the microwaves as the heat source instead of the traditional coal and natural gas heating.

Method for preparing chromium salt

The invention discloses a method for improving chromium conversion rate of a chromium salt rotary kiln by using calcium-free fillers, aiming at solving the problem that the rotary kiln accretion removing effect of the existing fillers is not good. The method comprises the following steps of: roasting chromite, sodium carbonate and calcium-free chromium slag in the rotary kiln, crushing, wet grinding and leaching clinker, classifying the obtained slurry into coarse chromium slag slurry and fine chromium slag slurry, and filtering and washing the coarse chromium slag slurry through a rubber belt type filter to obtain coarse chromium slag; filtering and washing the fine chromium slag slurry through a pressing filter to obtain fine chromium slag which is used for smelting chromium-containing cast iron; conveying the coarse chromium slag to a sunlight warm shed for storage; drying the coarse chromium slag which is stored for 6-24 months; and grinding the dried coarse chromium slag to the size below 74 micrometers and proportionally returning the slag into the chromium salt rotary kiln for roasting. The method has the key significances that after the coarse chromium slag is stored and weathered for a certain period, the chromium conversion rate of the chromium salt rotary kiln can be improved from 70 percent to 80-85 percent, the utilization ratio of the chromite is improved and the production cost is reduced.

Method for improving chromium conversion rate of chromium salt rotary kiln by using calcium-free fillers

The invention discloses a method for producing sodium chromate by roasting chromium ore and a small amount of soda. The method is characterized in that chromium ore and calcined soda are mixed, wherein the added quantity of the calcined soda is 35% to 45% of theoretical required amount for complete reaction with dichromium trioxide in the chromium ore; then the mixture is added to a rotary kiln for first roasting, the temperature of materials at a hot space in the kiln is 1000 DEG C to 1050 DEG C, wrought materials are cooled and leached to obtain a sodium chromate leaching solution and firstchromium dregs; the first chromium dregs are dried and crashed for second roasting with newly added calcined soda, the use amount of the calcined soda is 30% to 50% of theoretical required amount forcomplete reaction with the dichromium trioxide in the first chromium dregs; the sodium chromate leaching solution and second chromium dregs can be obtained through roasting and leaching processes, the second chromium dregs, limestone and newly added calcined soda are roasted for the third time, the use amount of the calcined soda in the third roasting is 35% to 75% of theoretical required amount for complete reaction with the dichromium trioxide in the second chromium dregs, and the use amount of the limestone is 2% to 5% of the sum of weight of three raw materials of the second chromium dregs, the calcined soda and the limestone; and the sodium chromate leaching solution and third chromium dregs are obtained after leaching. By adopting method of the invention, the utility ratio of the calcined soda is also enhanced greatly.

Method for producing sodium chromate by roasting chromium ore and small amount of soda

The invention discloses a method for jointly producing chromium salt and ferrochromium alloy by sintering with the wet-fire methods, comprising the following steps: grinding coarse ferrochromium ore into fine ferrochromium ore powder; mixing the fine ferrochromium ore powder and sodium carbonate into mixture, and sintering the mixture into primary sintered clinker; extracting primary sodium chromate solution from the primary sintered clinker and obtaining the left primary chromium slag; separating, sintering and crushing the primary chromium slag into primary chromium slag powder, and mixing the primary chromium slag powder and sodium carbonate into mixture, and sintering the mixture into secondary sintered clinker; extracting secondary alkaline sodium chromate solution from the secondary sintered clinker and obtaining the left secondary chromium slag; adding acidic solution to neutralize the alkaline sodium chromate solution; adding sodium dichromate to the sodium chromate solution, adjusting the acidifying with sulfuric acid to form sodium dichromate solution, and separating sodium dichromate crystals from the sodium dichromate solution; mixing the secondary chromium slag and iron ore with coke powder and auxiliary materials and sintering the mixture into sintered ore; and mixing the sintered ore and coke in a blast furnace to smelt the ferrochromium alloy.

Method for jointly producing chromium salt and ferrochromium alloy by sintering with wet and fire methods

The invention discloses a method for removing vanadium in chromic salt production by utilizing lime. The method comprises the following steps of: generating a calcium vanadate precipitate by utilizing calcium produced in a lime hydrolysis process, wherein lime is used as a raw material; and filtering and separating so that the content of vanadium in a sodium chromate leaching solution is less than 0.005g/L, the vanadium removing efficiency is greater than 99%, and the quality requirements are achieved. The method provided by the invention can be widely applied to industrial production and has the beneficial effects that (1) calcium used for removing vanadium is derived from lime, and the raw material is easy to obtain and low in price; (2) the reaction temperature is low, the energy consumption is less in a vanadium removing process; and (3) after the vanadium removing process is finished, a reaction product is easy to separate, waste water and waste residue are not generated in the reaction process, and the technological operation is simple and convenient; and (4) the recovery and profit of vanadium are realized.

Shun Liu

Papers

Method for producing sodium chromate by roasting chromium ore and small amount of soda

Method for jointly producing chromium salt and ferrochromium alloy by sintering with wet and fire methods

Method for removing vanadium in chromic salt production by utilizing lime