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

该项目旨在开发一种新的、更环保的硫化镍精矿处理工艺。今天，精矿被送到镍冶炼厂，在那里用空气氧化释放二氧化硫，形成固体镍焙烧。然后将这些焙烧送到电炉中在非常高的温度下冶炼，然后在排放SO2的转化器中进一步氧化。加拿大使用这一工艺的两家镍冶炼厂排放大量二氧化硫和二氧化碳，消耗大量电力。在调查过程中，目的是消除镍冶炼厂的大量废气污染。建议发展两步焙烧，一段焙烧形成氧化铁，二段焙烧形成镍、铜、钴硫酸盐。然后将有价值的金属硫酸盐溶解在水溶液中，然后对金属镍、铜和钴进行旁路提纯、分离和回收。如果能够做到这一点，将大大降低镍冶炼对环境的影响和电能消耗。将与淡水河谷-国际镍公司和斯特拉塔镍公司合作开发并实施一项测试计划。工业样本将在工厂人员的帮助下收集和鉴定。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成氧化铁，然后再将有价值的金属硫化物硫化。要做到这一点，预计需要不同温度和气体组成的两步焙烧操作。主要的技术挑战似乎是，可能会在每个颗粒周围形成一层致密的硫酸镍外壳，使气体难以通过，从而有效地减缓反应。我们将研究这一可能的现象，并评估解决这一问题的各种方法。将继续评估结果，如果结果是肯定的，将导致更大规模的中试试验

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