| Strontium and manganese tailings include gangue and waste residue. The gangue is mining waste rock of strontium or manganese Mine, and the waste residue is processing residue of strontium or manganese ore. Researches on the comprehensive use of strontium and manganese tailings have been made by Chinese workers. A lot of items has good application prospect, but their industrializations are slow. Thus, it is necessary that the comprehensive experimental researches have been done. The useful constituents can be retrieved, environmental probes of tailings contradiction resolved, and the contradiction between production development and environmental pollution relaxed. Environmental impact of tailings contradiction and recuperation proess on strontium and manganese have been researched in this paper, and properties and application in wastewater disposal on the secondary residues of strontium and manganese tailings explored.The resolving and leaching characteristics of strontium tailings have been studied. The results showed that the concentrations of soluble ions(strontium, bariumn and sulfides) and ions(strontium, bariumn and sulfides) in leaching solution, increased with the decrease of strontium waste residues(SWR) grain diameter. And the concentrations of strontium and bariumn in resolving and leaching solutions of strontium gangue increased as the grain diameter decreased. The concentration Sr and sulfide in dissolved solution and leaching solution of strontium tailing exceeded the wastewater discharge standard, but Ba concentration did not exceed. The resolving and leaching processes of soluble ions have fractal kinetics property.Effect of manganese tailings on environment has been researched. The concentration of manganese in leaching solution of manganese gangue increased with the decrease of diameter, but pH decresed. The 95% of grain diameter for gangue in manganese Mine is larger than 5mm. Effect of gangue contradiction on waters and soil environment is less. Static leaching process of manganese gangue has fractal kinetic property. Concentration of manganese in lecaching solution of electrolytic manganese waste residue(EMWR) is 615.8~619.6mg/L, and pH is about 5. These pollants excedded the limit of"Integrated wastewater discharge standard"(GB8978-1996).The effects of Mn in manganese tailings on growth, grain yield and manganese nutrition of wheat, pepper and radish have been studied by the methods of pot experiments. The results showed that the chlorophyll contents of the crops are increased, and economic characteristics improved, as the manganese tailings are added in soils. The manganese contents in seeds and stem leaf of wheat are respectively increased by 37.5%~55.8% and 12.6%~25.7%, those in fruit and stem leaf of pepper by 11.7%~23.4% and 33.9%~62.8%, and in seeds, stem leaf and root of radish by 20.0%~35.5%, 19.0%~29.2% and 13.5%~28.5%. The effect of manganese on yield increase of wheat is better than of pepper and radish. After the potted experiments, the manganese remaindered in soil is less than that in the original soil owing to plant absorption and loss of raining. Therefore, the manganese tainings could be comprehensively utilized as trace element fertilizer.Recuperation process of MnSO4 from EMWR has been contrastly researched. When the EMWR was leached with sulfuric acid, the leaching conditions are obtained by the orthogonal experiments. Namely, the liquid-solid ratio of the reaction system is 3:1, the concentration of sulfuric acid is 20%, the leaching temperature is 90℃and the leaching time is 3h. The results were shown that the leaching ratio of manganese is up to 96.2%. Finally, 91% of MnSO4 could be obtained by the method of two steps depuration. By the method of single factor, the effect of roasting conditions on Mn leaching ratio for treating EMWR with ammonium salt, has been researched. When the mixture of the EMWR and(NH4)2SO4 (1:1) was roasted for 1h at 450℃, Mn leaching ratio is up to 83%. Finally, 98% purity of MnSO4 has been obtained through remove of impurity. The process, economic efficiency and environmental benefit on the above two methods have been compared. From considering only the process, the roasting with ammonium salt is more suitable method.The optimized strontium conversation process of recycling strontium chloride from strontium residue were that the size of strontium waste residues was 0.054mm, the extraction time was 2 hour, the mass ratio between liquid and solid was 3.3 and the n (NH4Cl)/n(SrO) was 3.8. Under these conditions, the highest strontium conversation ratio reached to 96.1%. The optimized strontium conversation process of recycling strontium carbonate from strontium gangue is following as, the temperature was 90℃, the extraction time was 60 min and the concentration of Na2CO3 was 0.8 mol/L. Under these conditions, the highest strontium conversation ratio reached to 96.5%.The result of preparing strontium nitrate from celestite showed that the optimized strontium conversation conditions were, the concentration of HNO3 was 3.5-4.0mol/L, the n (HNO3)/n(SrCO3) was 2.01-2.29 and the mass ratio between liquid and solid was 5.2-6.4. Under these conditions, the strontium conversation ratio was 90.9%.The strontium ferrite is obtained with SrCO3, which is prepared by SrCl2 from strontium residue. The ferrite has face-centered cubic+close-packed hexagonal structure. There are the strong diffraction peaks of Fe2O3 in X-ray diffraction chart of the ferrite. The magnetic susceptibility of strontium ferrite decreased with the inecrease of pH as the mole ration of Fe3+/Sr2+ was 10.The activation of the secondary strontium residue can enhance the removing effect of Cr6+, and the removal ration increased with decrease of its grain diameter. The removal action has fractal kinetic characteristic. The proper disposal condition of Cr6+ has been obtained as following. Ratio of the secondary residue mass and wastewater volume is 1:25(g/ml), pH is 10, t is 40℃, and disposal time is 60min. And thus, removal ration of Cr6+ is 82.5%.The pore volume and specific surface area of manganese residue have been measured with using N2 adsorption method(ASAP2010). The feasibility of disposing wastewater by using manganese residue has been discussed on the light of absorption theory. The effect factors on disposal of copper-containing wastewater have been analyzed by the orthogonal experiment method. The results are shown that the micropores in surplus manganese residue roasted at 800℃, which is produce during the recovery process of Mn with ammonium salt method, is growth better. The specific surface area, micropore area percent and pore volume of this surplus manganese residue is the largest among the 6 test samples, and it is appropriate for removing the copper ion in the wastewater. The effect of pH on adsorption of Cu2+ is more obvious, but that of time on adsorption is less. The suitable adsorption conditions are 6 of pH, 1.5g of manganese residue and 2.5h of reaction time, and removal ration of Cu2+ is up to 96%. Adsorption process of Cu2+ in manganese residue obeys Freundlich experiential model.The adsorption kinetics of Pb2+ in rocks has been studied using ion selective electrodes and atomic absorption spectrophotometer. The results showed that the adsorption process is a fractal-like reaction. The saturated adsorptive capcity decreased as there is Na+ or K+ in the solution of Pb2+. |
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