从锑酸钠制备硫代锑酸锑的工艺研究

【作者】 杜新玲；

【导师】 杨天足；

【作者基本信息】 中南大学 ， 有色金属冶金， 2010， 硕士

【摘要】 本文针对我国对锑深加工产品硫代锑酸锑的需求,研究了用锑酸钠合成硫代锑酸锑的新工艺。新工艺采用硫化钠浸取锑酸钠制取硫代锑酸钠(五价锑),用含盐酸的氯化钠饱和溶液浸取锑白,制取三氯化锑(三价锑)之后,在HCl+NaCl+H2O的反应体系中合成硫代锑酸锑。该工艺有效解决了传统工艺存在的三价锑水解、硫对产品的污染以及反应后液对环境的污染等问题,同时具有较好的经济效益。研究了硫化钠浸取锑酸钠制取硫代锑酸钠的实验条件,确定了温度、硫化钠用量、浸出时间等条件对锑酸钠浸出率的影响。硫化钠用量为理论量的1.08倍时,锑的浸出率达到最高,当硫化钠用量超过理论量的1.08倍后,锑浸出率略有下降；锑的浸出率随温度升高和浸出时间的延长,锑的浸出率也随之增加；浸出滤液采取缓慢冷却,温度冷却至18-20℃,硫代锑酸钠即大部分结晶析出。得到了最佳实验条件：温度95℃、浸出时间3h、搅拌速度300r/min、硫化钠与锑的质量比为2.8时,锑的浸出率为97.42%,所得浸出液经过滤、缓冷结晶可得硫代锑酸钠产品,该产品既可做进一步生产硫代锑酸锑的原料,又可以作为产品销售。同时,研究了pH、NaCl浓度对三氯化锑水解的影响。结果表明,加入的总锑离子浓度一定时,随着pH的增大,达到平衡时溶液中的锑离子浓度都是急剧减小；随着总氯离子浓度的增加,溶液中的锑离子浓度显著增加,并且三氯化锑水解产物由易到难顺序依次为Sb4O5Cl2、SbOCl、Sb2O3、Sb(OH)3。在加入的总氯离子浓度为6mol/L时,其与锑离子的配合导致平衡时溶液中所含锑离子浓度也显著增加；在总锑离子浓度一定时,随着pH的增加,平衡时溶液中所含锑离子浓度减少。探索了合成硫代锑酸锑的反应体系,以及pH值、氯化钠浓度、温度、反应时间、洗涤等条件对合成硫代锑酸锑的影响。为避免三价锑水解,设计了HCl+NaCl+H2O的反应体系,体系中,NaCl饱和,将Sb(Ⅴ)和Sb(Ⅲ)以1：1的摩尔比缓慢滴加到反应体系中,过程不断搅拌,反应过程中以HCl和NaOH调整体系环境,维持pH值在2左右,并控制反应在室温下进行,将合成产物过滤后,用pH值为2的去离子水洗涤,在75℃左右烘干24h,得到了含锑总量为65.1%,含硫总量为34.2%的化学产品。半工业试验表明,产品的直收率为98.2%,其中锑的质量分数为64.1%,S的质量分数为33.8%,接近于理论含锑、硫总量65.55%、34.45%,达到了较好的产品质量。研磨后经差热、XRD谱图分析确定此红棕色产品为不是Sb2S3或Sb2S5和S的混合物,而是硫代锑酸锑。更多还原

【Abstract】 To meet the demand of China for the antimony thioantimonate, the intensive processing product of antimony, new technique of antimony thioantimonate prepared from sodium pyroantimonate is researched. The processing technique is as follows: sodium sulfantimonate (pentavalent stibium) is prepared by sodium pyroantimonate leached in sodium sulfide solution, antimony trioxide is leached with sodium chloride saturated solution and hydrochloric acid, after the antimony trichloride (tervalence stibium) and sodium sulfantimonate are prepared, they are added to the reaction system of HCl+NaCl to synthesize into antimony thioantimonate. The technique can solve the traditional technique problem of tervalence stibium hydrolysis, products pollution from sulphur and environment pollution from after-reaction liquid. Meanwhile, good economic benefits can be achieved.The experimental process, in which sodium sulfantimonate is prepared by sodium pyroantimonate leached in sodium sulfide solution, is studied. The effect of temperature, concentration of sodium sulfide and leaching time on leaching rate of sodium antimonite is made. When the dosage of sodium sulfide is higher than 1.08 times of the theory dosage, the leaching rate of sodium pyroantimonate begins to decrease from the highest value; with the higher temperature and the longer time, the leaching of sodium pyroantimonate increases;and then the leaching solution is cooled slowly, when the temperature is about 18-20℃,the sodium sulfantimonate can be filted.The experimental results show that the leaching rate can reach 97.42% when the optimum is adopted which the weight ratio of sodium antimonate and antimony is 2.8, and the sodium antimonate is leached at 95℃for 3 hours. After filtration,the crystals of sodium sulfantimonate are produced. The crystals can be used as the raw materials of antimony thioantimonate as well as the products to sell, which can bring good economic benefits.Meanwhile, the influences of pH and concentration of NaCl on hydrolysis of antimony trichloride are studied. The result shows that when the same concentration of antimony ions are kept in different conditions, the concentration of antimony ion in the solution decreases rapidly with the increase of pH value; antimony ion concentration in solution increases with the increase of total antimony ion, the hydrolysates production of antimony trichloride are Sb4O5Cl2、SbOCl、Sb2O3 and Sb(OH)3 by order. When the total chlorine ion concentration is up to 6mol/L, the coordination of antimony ion leads to increase of the antimony ion in the balance solution; when the total antimony ion concentration is added in the same higher dosage, the antimony ion concentration in balance solution decreases with the increase of pH value.The influences of the reaction system of HCl+NaCl, pH value, concentration of sodium chloride, temperature, time and washing on the antimony thioantimonate synthesizing are researched. In order to avoid hydrolysis of tervalence stibium, the reaction of HCl+NaCl+H2O is designed. In the reaction system, NaCl is saturated.Then SbⅤ+ and SbⅢ+, whose mol ratio is 1:1, are dripped into the reaction system and continuously mixed. In the reaction process, HCl and NaOH are used to keep pH value at 2 and the room temperature in the reaction system. The filtrated products are washed with de-ionized water, whose pH value is 2, dried at 75℃for 24 hours. The chemical analyse shows that, the antimony content is 65.1% and the sulpur content is 34.2%.In the half industrial experiment, the direct recovery rate is 98.2%, antimony content is 64.1% and sulphur content is 33.8%, which are close to theoretical content of antimony(65.55%) and sulphur content(34.45%). The brick-red product is analyzed by XRD spectrogram which shows that the product is not compound of Sb2S3、Sb2S5 and S but antimony thioantimonate.更多还原