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Research on the Comprehensive Utilization of Wastewater from the Molybdenum-tungsten Extraction Process

Author: DengHuan
Tutor: TangJianWei
School: Zhengzhou University
Course: Chemical processes
Keywords: Mineral Processing Wastewater Fluorine Phosphorus Calcium hydrogen phosphate Solubility Cooling and crystallization
CLC: X756
Type: Master's thesis
Year: 2011
Downloads: 54
Quote: 0
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Abstract


Tungsten, molybdenum is a very important industry both rare metal elements, while the trace elements molybdenum or crop growth. Luoyang Molybdenum Group Co., Ltd. is extracted with hydrochloric acid of tungsten and molybdenum beneficiation process, there are a large number of acidic beneficiation wastewater. If left untreated wastewater directly discharged into water bodies and cause serious pollution and destruction, will mine the surrounding environment and ecology. In this study, the beneficiation wastewater treatment, this beneficiation wastewater resource utilization. Mainly in the acidic wastewater containing elements of P, F, Ca, Cl, literature review combined wastewater characteristics, quicklime and prepared DCP manufactured, the filtrate then Shen phosphorus cool crystal production calcium chloride, crystallized calcium chloride filtrate after looping back to the beneficiation process uses hydrochloric acid extraction of tungsten and molybdenum. The main subject from Shen phosphorus, in addition to two aspects of the calcium to carry out research work, specific programs, and conclusions are as follows. (1) Shen phosphorus: research one step Shen phosphorus preparing fertilizer grade DCP and two-stage step-by-step sink phosphorus preparation of fertilizer grade dicalcium phosphate feed grade DCP two processes. One step Shen phosphorus preparation fertilizer grade DCP: stirring speed 700r · min-1, the reaction temperature is 35 ℃, reaction time 2h, digestion solution of calcium water (WCaO/H2O, mass ratio) of 1:5, and to a pH of between 6 to 7, the phosphorus content in the wastewater can be reduced to below 0.4g / L, while available phosphorus content of about 25% of the fertilizer grade DCP; process step-by-step Shen phosphorus, step by adding an appropriate amount of lime to remove the fluoride in the wastewater, studies show that: in oscillation speed 200r · min-1, the reaction temperature of 45 ℃, reaction time 3h process conditions can be obtained by adding the right amount of lime P2O5 and F-quality DCP production of the feed grade (WP2O5 / F) ≥ 230 qualified filtrate, and more than 90% of the waste liquid phosphorus remain in the filtrate as the Next the raw materials of the preparation of feed-grade DCP found HG-can also be obtained T 3275-1999 requirements for qualified fertilizer grade DCP products; the second step preparation of feed grade DCP promotions process conditions for the reaction temperature of 50 ° C, the reaction time 1h, stirring speed 600 r · min-1 for the WCaO/H2O 1:4, this phosphorus almost all precipitate out and available to meet the requirements of GB-T 22549-2008 Ⅰ products feed-grade DCP. By the XRD pattern shows that the step and precipitate after the CaF2, Ca5 (PO4) 3F, and CaHPO4 mainly two step and the solid product was only detected CaHPO4 · 2H2O crystal diffraction peak. \By the solubility of calcium chloride in the hydrochloric acid of different concentrations on the experimental results of the model associated with known to better conform to the polynomial equation. (3) crystal: the impact of the of intermittent dynamic method for the determination of calcium chloride in in Shen phosphorus filtrate cooling crystallization kinetics, the effects of the cooling rate, stirring rate of operating conditions on the growth rate and crystal nucleation rate. Independent of the chosen granularity growth model, and intermittent dynamic method of moments transform method, regression analysis of the crystallization kinetics data, the growth rate equation of calcium chloride cooling crystallization process and the nucleation rate equation.

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CLC: > Environmental science, safety science > Processing and comprehensive utilization of waste > Mining, metallurgical industry,waste disposal and comprehensive utilization > Metallurgical Industry
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