Selective sulfation roasting of Ni concentrate to minimize off-gas pollution

本项目旨在开发一种更环保的处理硫化镍精矿的新工艺。如今，精矿被送到镍冶炼厂，在那里与空气氧化，释放出二氧化硫，形成固体镍煅烧物。然后将煅烧物送到电炉在非常高的温度下熔炼，然后在转炉中进一步氧化，释放出二氧化硫。加拿大的两家镍冶炼厂使用这种工艺会排放大量的二氧化硫和二氧化碳，并消耗大量的电力。在所研究的过程中，目的是消除镍冶炼厂的大量废气污染。提出了两步焙烧技术，第一步焙烧形成氧化铁，第二步焙烧形成硫酸镍、铜和钴。然后将有价值的金属硫酸盐溶解在水溶液中，然后进行提纯、分离和回收金属镍、铜和钴。如果能做到这一点，将大大降低镍冶炼的环境影响和电能消耗。与Vale-Inco和Xstrata Nickel合作，将开发和实施一个测试程序。工业样品将在工厂人员的帮助下收集和表征。实验室测试的主要重点将是确定如何首先选择性地将硫化铁氧化为氧化铁，然后将有价金属硫化物硫酸盐化。要做到这一点，预计需要在不同温度和气体成分下进行两步焙烧操作。主要的技术挑战似乎是每个粒子周围可能会形成一层致密的硫酸镍壳，这使得气体很难通过，从而有效地减缓了反应。我们将研究这种可能的现象，并评估各种方法来解决这个问题。结果将持续评估，如果是积极的，将导致更大规模的中试工厂测试

This project aims at developing a new and more environmental friendlyprocess to treat nickel sulphide concentrate. Today, concentrate is sent to nickel smelters where it is oxidized with air to release SO2 and form a solid nickel calcine. This calcine is then sent to electric furnaces for smelting at veryhigh temperature, beforebeing further oxidized in converters emitting SO2. The two nickel smelters in Canada that use this process emit large amounts of SO2 and CO2, and consume significant amounts of electricity.Inthe process to be investigated, the aim is to eliminate a large amount of off-gas pollution from nickel smelters. It is proposed to develop two-step roasting with the first roaster forming iron oxides and the second roaster forming nickel, copper and cobalt sulfates. The valuable metal sulphates will then be dissolved in an aqueous solution, followed bypurification, separation and recoveryof metallic nickel, copper and cobalt. If thiscan be done, the environmental impacts and electric energyconsumption of nickel smelting will be greatly lowered.Incollaboration with Vale-Inco and Xstrata Nickel, a test program will be developed and carried out. Industrialsamples will be collected and characterized with the help of plant personnel. The main focus of the laboratory tests will be to determine how to first selectivelyoxidize the iron sulfides to iron oxides, then to sulphate the valuable metal sulfides. To do this, it is expected that a two-step roasting operation with different temperatures and gas compositions are required. The main technical challenge seems to be that a dense shell of nickel sulphate mayform around each particle, making it difficult for gases to pass through, effectivelyslowing down the reactions. We will studythis possible phenomenon and evaluate various methods to counteract this problem. The results will be evaluated continuouslyand if positive, lead to pilot-plant testing on a larger scale