芒市硅酸镍矿回转窑直接还原制备镍铁半工业试验研究

Semi-Industrial Experimental Study of Preparation Ferronickel by Rotary Kiln Direct Reduction on Mangshi Silicate Nickel Ores in Yunnan

芒市硅酸镍矿原矿含Ni 1.02%,Fe 8.94%,MgO 31.11%,属于典型的高镁低铁型硅酸镍矿石。因矿石中氧化镁的含量较高,依据小型试验研究结果,在焙烧过程中添加自行研发的CX促进剂和ZX助剂改善镍的还原,提高镍铁的转化率;利用镍、铁属于铁磁性金属及易溶于铁的氧化物的特性,添加赤铁矿作为镍的活化剂,为形成镍铁提供活化载体,进而提高镍铁产品指标。为验证直接还原—重选—磁选的选冶联合工艺流程处理芒市硅酸镍矿的可行性,采用Φ1200 mm×15000 mm的回转窑进行半工业验证试验研究,经过回转窑焙烧条件试验得出,回转窑高温带B段1150～1200℃、C段950～1000℃、焙烧时间90 min、焦炭用量20%、促进剂CX用量20%、助剂ZX用量1%、赤铁矿用量15%比较合理,镍铁产品指标也比较理想。为进一步验证回转窑焙烧综合条件的稳定性及工艺的可行性,在所得到的焙烧综合条件下进行回转窑连续72 h工艺参数稳定试验,焙烧产品采用重选—磁选工艺回收镍铁并得到了镍品位12.29%,含Fe 30.05%,镍回收率为90.99%的全工艺流程镍铁产品指标。因此,回转窑直接还原—重选—磁选工艺处理芒市高镁低铁型硅酸镍矿石具有良好的效果,同时对类似的硅酸镍矿石的处理也有一定的指导作用。

The Mangshi silicate nickel crude ores in Yunnan contained Ni grade of 1.02%, Fe grade of 8.94%, and MgO grade of 31.11%, which belonged to the typical type of silicate nickel ore high in magnesium and low in iron. Because magnesium oxide content was rather high, according to the small test research results, in the roasting process adding CX accelerating agent and ZX addition agent by oneself research and development to improve reduction of nickel and enhance ferronickel conversion rate. Using the character- istic of both nickel and iron belonging to ferromagnetism metals and easy dissolving in oxide of iron, adding hematite as activating a- gent, providing activated carrier for forming ferronickel, and then improving the ferronickel product index. Semi-industrial experimental study was conducted with 01200 mmx 15000 mm rotary kiln to check the feasibility of separation and metallurgy combination flowsheet of direct reduction-gravity separation-magnetic separation to process Mangshi silicate nickel ores. The high-temperature zone was 1150 - 1200 ℃ in B sect, 950 - 1000 ℃ in C sect, roasting time was 90 rain, dosage of coke was 20%, dosage of accelerator （CX） was 20% ,dosage of additives （ZX） was 1%, dosage of hematite was 15%, after the roasting condition experiment of rotary kiln, the ferronickel product index was ideal. Under the roasting comprehensive condition, the rotary kiln 72 h continuous stable technological parameter was conducted to further check the stability of roasting condition and feasibility of technology, adopting gravity separation-magnetic separation technology recovery of ferronickel from roasting products and getting the whole technological process ferronickel product index： grade of nickel was 12.29%, content of iron was 30.05%, recovery of nickel was 90.99%. Therefore direct reduction-gravity separation-magnetic separation technology by rotary kiln had the favorable effect on processing the Mangshi silicate nickel ore type of high in magnesium and low in iron, and provided a certain guidance to process the similar silicate nickel ores.