Research On Novel Methods Of Value-added Metallurgy Of Associated Elements Arsenic, Antimony, Bismuth And Rhenium In Copper Smelting Process

China is the world’s largest producer and consumer of refined copper. Copper ore and copper renewable resource contains a large number of associated elements with great economic value. However, China’s copper smelting process has few comprehensive recovery of valuable elements, comprehensive recovery efficiency is low, technical level is relatively backward, and rare resource has a great loss. The products from recycling elements are mostly primary, and result to a serious environmental pollution. Whether from the sustainable development of copper smelting industry or from the environmental protection, it has important practical significance to research the recycle and comprehensive utilization of associated elements in copper smelting. Therefore, in this paper, the project "Resaech on novel methods of value-added metallurgy of associated elements arsenic, antimony, bismuth and rhenium in copper smelting process" was put forward, and the recovery and deep processing of the associated elements was studied systematically, the results are as following:The copper and associated elements in copper smelting process were taken as research object, the mathematical model of multi-phase equilibrium system of the matte smelting was established, and the effects of parameters on the behavior of each element were investigated. The results show that:copper exists mainly in smelting slag by Cu2O when copper matte grade is higher than76%; the gas phase S2(g) can be eliminated by strengthened oxygen-rich smelting and improving copper matte grade; the Fe3O4content in slag increases with the increse of Fe/SiO2value and contents of copper, iron in copper matte; with the increase of copper matte grade, the distribution ratio of As in copper matte phase increases, and the distribution ratios of Sb, Bi, Sn, Co, Ni increase in the slag phase; increasing the concentration of oxygen will increase the allocation amount of As, Sb in the slag phase and the amount of Bi, Sn in the matte phase; in addition, the distribution ratios of Sb, Bi, Sn in the copper matte increase with the increase of Fe/SiO2.A new technical route of recycling arsenic and preparing arsenic trioxide from copper metallurgical off-gas washing wastewater was proposed. First, the arsenic wastewater was treated by using sodium sulfide as a precipitator, and the precipitation rate of arsenic and copper reached94.93%and99.91%, respectively. The obtained arsenic sulfide slag was leached by sodium hydroxide. The arsenic and copper leaching rate reached95.90%and0.087%, respectively, at the optimum parameters:reaction temperature of90℃, solid-liquid ratio of1:6, reaction time of1.5h and molar ratio of NaOH and As2S37.2:1. The study of arsenic sulfide slag alkali leaching kinetics shows that the reaction of As2S3in NaOH solution was controlled by unreacted shrinking core diffusion, and its kinetic equation is1-(1-xB)2/3=kt k=1.868×103exp3682/RT. The oxidative desulfurization of alkaline leaching liquid was carried out by using air as an oxidant. The sulfur with a purity of78.013%was obtained at the reaction time of10h, reaction temperature of30℃, air flow rate of120g·L-1, catalyst of1.5g·L-1hydroquinone and0.5g-L-1potassium permanganate, and surfactant of0.13g·L-1sodium lignosulphonate. Finally, the oxidation liquid was reduced by SO2. When the pH value is0, the reaction time is1h, the reaction temperature is30℃, and the arsenic concentration is60.00g·L-1, the As2O3content of reduction product reached95.4%, and the arsenic recovery was up to95.46%.The associated elements antimony in copper smelting was recycled and antimony oxide was prepared for the first time by a hydrochloric acid leaching-hydrolysis-dechlorination-transformation process using high arsenic antimony oxide dust from bismuth refining as raw material. The lg[Men+]T-pH and Men+concentration-pH diagram of Sb, As, Bi, Pb were drawn by thermodynamic calculations, which provides a theoretical basis for the leaching of crude antimony oxide fumes. The crude antimony oxide fumes were leached by hydrochloric acid, and the leaching rate of antimony reached99.5%at the liquid-solid ratio of3:1, reaction time of4h, reaction temperature of80℃, and hydrochloric acid amount of1.2times to the theoretical amount. Then the leaching solution was hydrolyzed. When dilution ratio is10:1, the hydrolysis rate of Sb3+reached98.25%, and the As, Pb, Bi impurity contents of the hydrolyzate antimony oxychloride were2.017%,0.505%, and1.085%, respectively. The first hydrolyzate Sb4O5Cl2was dissolved in hydrochloric acid and hydrolyzed for the second time, and the As, Pb, Bi impurity contents of the second hydrolyzate antimony oxychloride were0.929%0.231%,0.256%, respectively. If EDTA was added in the second hydrolyzation, the As, Pb, Bi impurity contents were0.092%,0.044%, and0.133%, respectively. The last cubic crystal Sb2O3from the second antimony oxychloride with a prismatic shape, purity of99.47%, whiteness of93.47%, and volume average particle size of0.954μm can be obtained at reaction temperature of20℃, liquid-solid ratio of1.6:1, reaction time of1h, EDTA of1wt.%antimony oxychloride, and ammonia of1.2times theoretical amount.The theoretical calculations of bismuth evaporation rate in the preparation of bismuth oxide by decompression evaporation-oxidation method was arried out, which indicates that the bismuth evaporation rate can be up to5g/(cm2-min) at T=1140℃. The thermodynamic calculation results of bismuth oxidation show that the standard molar Gibbs free energy of oxidation reaction of bismuth vapor and bismuth melt are approximately the same order of magnitude, and far less than zero. In the experiment, the evaporation and oxidation processes were carried out separately, in order to minimize the occurrence of side reactions Bi(g)+Bi2O3(l)=3BiO(1) and eliminate the effect of bismuth melt oxidation on the formation of bismuth vapors.Ultrafine (3-Bi2O3spherical powder was prepared by decompression evaporation-oxidation method using4N refined bismuth from copper smelting process as raw materials. The effects of process conditions on the size, shape and phase of Bi2O3powder were studied. The results show that:β-Bi2O3with average particle size less than1μm can be obtained at plasma generator temperature of1200℃, pressure of0.08MPa, nitrogen flow of12L/min, oxidation chamber oxygen flow of12L/min, and cooling gas flow of120L/min. The industrialization preparation of the β-Bi2O3was successfully achieved by using DC arc plasma heating-decompression evaporation-oxidation method. The P-Bi2O3with a spherical shape, an average particle size less than1μm, ignition loss of less than0.5%, and purity greater than or equal to99.9%was obtained.The study of extract rhenium from the final reduction solution in copper smelting process and preparing rhenium powder by CVD method was carried out. Using N235as extraction agent, sec-octanol as inhibitors, kerosene as diluent and ammonia as stripping agent, the rhenium extraction rate is up to97.8%at the phase composition of20%N235+40%kerosene+40%sec-octanol (volume ratio), phase ration O/A of1/30, extraction time of5min, extraction series of4, and recycling of organic phase. The ammonium perrhenate with purity greater than99%was obtained after the stripping of ammonia and crystallization of ammonium perrhenate. The ultrafine rhenium powder was prepared by CVD method. The metal rhenium powder with spherical shape, laser particle size distribution range of100-800nm, laser particle size D50value of100nm, BET specific surface area of4.37m2/g, oxygen content of0.45wt.%was obtained at the evaporation zone temperature of400℃, carrier gas (N2) flow of60L/h, oxygen flow rate of60mL/min, reduction zone temperature of1000℃, hydrogen excess coefficient of6, and no partition existance.The preparation of Re2O7by thermal decomposition of ammonium perrhenate at controlled temperature and oxygen pressure was put forward for the first time. The theoretical research of the thermal decomposition of ammonium perrhenate was carried out. The results show that the decomposition of Re2O7to ReO3and ReO2can not happen in673.15-1273.15K when the oxygen potential is greater than1013.25Pa. The DSC-TGA results and thermal decomposition volatile experiments of ammonium perrhenate confirmed that the ammonium perrhenate can decompose to Re2O7completely by controlling the temperature and oxygen partial pressure conditions.