基于循环经济的低品位难处理氧化锌矿选冶联合新工艺研究

【作者】 李明晓；

【导师】 张文彬；

【作者基本信息】 昆明理工大学 ， 矿物加工工程， 2011， 博士

【摘要】 我国是锌金属第一生产大国和消费大国,锌矿资源紧缺问题已日益凸现,每年约有三分之一的锌原料需要进口,资源供应不足已成为制约社会可持续发展的重要因素。然而,我国锌矿资源尤其是低品位高杂质的氧化锌矿由于缺乏高效的加工处理技术而没有得到合理利用。云南兰坪铅锌矿具有矿石品位低、结构复杂、泥化严重、碱性脉石含量高等特点,是一种典型的难处理矿石,其氧化锌矿中的锌金属储量约为400万吨,单就氧化锌矿而言,规模居世界第一位。国内有关单位曾多次进行选矿技术攻关,虽然在小型试验和扩大连选试验中取得了良好的技术指标,但未能进行工业化生产。因此,开采出来的难处理矿石只能堆存甚至废弃,目前已经堆存的氧化锌矿石总量就有3000多万吨。主要原因有以下两点：第一,该矿石若采用单一浮选法处理,虽然可取得较高品位的锌精矿,然而回收率太低,不利于氧化锌的回收,另外还有大量的锌金属损失在矿泥中,造成了资源的浪费,与循环经济所倡导的资源综合利用的目的背道而驰；第二,若采用湿法酸浸工艺直接对原矿进行处理,由于碱性脉石含量高,这样不但会造成酸耗急剧上升,还会增加湿法炼锌的能耗,同样违背了循环经济的节能和降耗原则。因此,提高兰坪氧化锌矿的回收率,尽快解决兰坪以及类似氧化锌矿石的高效利用问题,对于我国低品位难处理氧化锌矿资源的开发以及相关产业的发展具有重大意义。本论文在发展循环经济的技术背景下,针对兰坪低品位氧化锌矿的处理难点,创新性地提出了一种选冶联合工艺流程,即“浮选脱钙—预富集—湿法炼锌”工艺。通过系统和深入的试验研究,采用新工艺,可获得全流程总锌回收率为86.56%的良好技术指标,而且氧化锌粗精矿(湿法酸浸给料)的耗酸量仅为2.55t/t·Zn,大幅度降低了湿法炼锌的耗酸量。新工艺技术符合循环经济的三大原则,既发挥了浮选脱杂的优势,又发挥了酸浸能够充分回收氧化锌矿物的优势,整体上取得了提高资源利用率与节能、降耗和减排的效果。在废水零排放的苛刻条件下,通过采取有效的解决措施,实现了浮选回水和冶炼废水的循环利用。湿法炼锌技术已是成熟工艺,因此,本论文对选矿适度富锌脱钙进行了重点研究。通过浮选工艺的选择及优化、磨矿工艺的改进、药剂的协同作用以及改性捕收剂HHA的使用,最终获得了指标优异的氧化锌粗精矿：品位和回收率分别为18.72%和91.13%。作为后续湿法酸浸的给料,该粗精矿中的氧化钙含量由原矿中的22.23%降到了12.31%,脱除了高达77.28%的氧化钙杂质,实现了保锌脱钙的目标。论文采用响应曲面法对浮选工艺条件进行了优化,选择了合适的泥砂分选工艺条件。大量试验研究结果表明,原生矿泥的预先脱除、改性捕收剂HHA的使用、碳酸钠和硫化钠的联合使用是该浮选工艺成功的关键。在浮选机理方面,重点研究了硫化钠与菱锌矿和异极矿之间的硫化反应动力学,推导出了不同pH值(9～11)下硫化钠与菱锌矿和异极矿之间的硫化反应速率方程,速率方程均属于一级反应；发现异极矿在硫化钠高用量条件下才能达到较好的回收率,其原因在于异极矿只能吸附较少的硫化钠参与硫化反应,而且反应速率很慢,表明异极矿较难硫化。用纯矿物实验证实了碳酸钠对异极矿具有活化作用,碳酸钠和硫化钠的联合使用不仅可以提高异极矿的回收率,而且还能有效抑制方解石的上浮。本文提出的选冶联合新技术对于提高低品位难处理氧化锌矿的利用水平、缓解锌资源短缺和实现锌产业的可持续发展有重大意义。更多还原

【Abstract】 China has become the largest country of producing and consuming zinc metal. Zinc resources in China have become more and more shortage as time goes on, and about one third of zinc raw material has to be imported, which has become one of the major factors to constrain sustainable development of society. Zinc resources, however, have not been utilized reasonably in China, especially the low-grade zinc oxide ore with high impurities like calcium and magnesium.Being a typical refractory ore in Yunnan province, Lanping lead-zinc ore has the characteristics of low grade, complex mineral textures, heavy sliming and high-content alkaline gangues. The zinc metal reserve of zinc oxide ore in the said area reaches about 4-million tons, which ranks the largest one in the world. The domestic research institutes have investigated it for many years, good flotation performance has been achieved in laboratory and pilot test, but the processing technology has not been put into commercial operation. Therefore, the run-of-mine ore has to be piled up or discarded, which has a capacity of 30-million tons up to now. There are two main reasons:first, if the ore is treated just by flotation, the high-grade zinc concentrate can be obtained, but its recovery is very low due to the poor processing efficiency of zinc oxide. In this case, the massive zinc metal are lost in the slime, resulting in waste of resources, which conflicts with the comprehensive utilization of resources advocated by circular economy. Second, the raw ore is directly processed by hydrometallurgy, not only will high-content alkaline gangues consume a large amount of acid, but also increase the energy consumption of zinc hydrometallurgical process. Therefore, it is necessary to improve the recovery of low-grade refractory zinc oxide ore and realize better utilization of the said ore as soon as possible, which has profound significance on utilizing the low-grade refractory ore and related industry in China.Under the technical background of circular economy, the new dressing-metallurgy combination process has been put forward, namely "calcium removal by flotation-preconcentration-zinc hydrometallurgy". The experimental results of studies on new dressing-metallurgy combination process signify that 86.56% recovery of total zinc for whole flowsheet that is the very good technical index. The acid consumption of rough zinc oxide concentrate is only 2.55t/t·Zn that is very low, which reduces significantly the acid consumption of zinc hydrometallurgy process. According with the three principles of circular economy, the new technology that can give full play advantage of flotation removing calcium as well as sulfuric acid leaching to recover zinc oxide minerals, and the goal of energy saving, emission reduction, comprehensive utilization of resources will be achieved. The recycling of wastewater produced in the dressing-metallurgy combination process has come true by using effective measures ultimately.The technology of zinc hydrometallurgy is a mature process, therefore, calcium removal by flotation and zinc preconcentration are researched mainly by the paper. The experimental results of studies on flotation process show that good performance can be obtained by using the separation process between slime and ore sand in the way of desliming prior to grinding. On the conditions of optimizing flotation process and adopting the efficient collector—HHA, good flotation index of rough zinc oxide concentrate can be gained:grade and recovery are 18.72% and 91.13% respectively, while the contents of calcium oxide in rough zinc oxide concentrate have declined from 22.23% to 12.31%. In this case,77.28% calcium oxide impurities in the ore have been removed. The process conditions of flotation are optimized by adopting response surface methodology, which provide the theoretical basis for choosing appropriate process conditions of slime and ore sand separation. A large number of experimental results show that pre-removing primary slime, using the modified collector—HHA, combined use of sodium carbonate and sodium sulfide are the key factors of success for the flotation process.The kinetics of sodium sulfide reacting with smithsonite and hemimorphite are studied by the paper in the flotation mechanism, and the sulfidation reaction rate equations on the condition of pH=9,10,11 respectively belong to the first-order reaction. It can be found that good recovery is achieved in high dosages of sodium sulfide for hemimorphite as a result of less adsorption and slow reaction rate on sodium sulfide. So it can be confirmed that more sodium sulfide are consumed due to high-content zinc silicate in the zinc oxide ore. The pure minerals experiments approve that recovery of hemimorphite can be enhanced by joint use of sodium carbonate and sodium sulfide, while calcite can be restricted strongly.All in all, the new process has great significance for increasing the utilization of low-grade refractory zinc oxide ore, releasing the shortage of zinc resources and realizing the sustainable development of zinc industry.更多还原