【作者】 孙伟；

【导师】 杜雪岩； 刘国平；

【作者基本信息】 兰州理工大学 ， 材料工程（专业学位）， 2019， 硕士

【摘要】 铬矿是用来生产铬铁合金的重要原料。但是铬矿是中国紧缺的矿产资源,2011年全国探明铬铁矿资源储量1161.1万吨,中国93%铬矿需要依靠进口,2014年的铬矿产量2868万吨,需要消耗商品级铬矿石约2900万吨,出现了供不应求。如何使用价格较低的粉矿和国内贫矿,降低生产成本,提升企业竞争力是主要研究的方向。本研究主要以铬铁精矿和低品位铬矿为原料,通过烧结、压球等方式搭配入炉生产,获得最优的配料结构和操作参数制度,来达到降低生产成本的目的。本文对铬精粉矿进行烧结实验,并采购一定量的压球、球团矿进行电炉冶炼高碳铬铁工艺研究,本实验研究主要内容包括铬铁精矿粉烧结试验和电炉还原熔炼各产品生产试验工艺参数的优化,并对铬铁精矿烧结固结机理进行了研究。铬铁精矿烧结试验研究表明:在点火温度1100±50℃,点火时间300s,点火负压6000pa,烧结负压10000pa,料层高度700mm,水分9-11%的试验参数下,南非铬矿粉烧结最佳燃料配比为13%。膨润土作为粘结剂,试验中4%配加能强化南非铬矿粉制粒效果,提升料层透气性,优化烧结过程指标,实验室利用系数最高达0.56t/台.h,工业生产应用适当提高膨润土配比至6%。铬矿粉经过烧结工艺,铬矿存在不同程度的还原,烧结矿中存在金属铬,铬矿还原度在13.76%²4.88%之间。电炉生产实践表明:Mg²+或MgO/Al₂O₃很高的炉渣在出炉后随温度下降到1600℃左右时易产生强烈结晶,易使合金颗粒来不及下沉而夹杂在渣中,导致金属回收降低,通过实践探索,生产中MgO/Al₂O₃控制在1.3最为合适。冶炼过程中,冶炼前期回收率提升较快,但是进入精炼期后,回收率提升幅度迅速降低,控制单炉冶炼时间烧结矿和压球在140min以内,控制压球在160min以内。理论渣温在1700℃时,控制渣过热度在120-150℃区间最优。更多还原

【Abstract】 Chromite is an important raw material for producing ferrochromium alloy.However,chromium ore is a scarce mineral resource in China.In 2011,the national proven reserves of chromium ore resources were 11.611 million tons.93% of China’s chromium ore needs to rely on imports.In 2014,the chromium ore output was 28.68 million tons,and the consumption of commercial grade chromium ore was about 29 million tons,resulting in a shortage of supply and demand.How to use low-priced fine ore and domestic lean ore to reduce production costs and enhance the competitiveness of enterprises is the main research direction.In this study,ferrochrome concentrate and low-grade chromium ore are used as raw materials,and the optimal mix structure and operation parameters are obtained by sintering and pressing balls,so as to reduce production costs.In this paper,the sintering experiment of chromium concentrate is carried out,and a certain amount of balls and pellets are purchased to study the process of smelting high carbon ferrochromium in electric furnace.The main contents of this experiment include the sintering experiment of ferrochromium concentrate powder and the optimization of technological parameters of production test of various products in electric furnace reduction smelting,and the sintering and consolidation mechanism of ferrochromium concentrate is studied.The sintering test of ferrochrome concentrate shows that the optimum fuel ratio of South Africa chrome ore powder sintering is 13% under the test parameters of ignition temperature 1100±50℃,ignition time 300 s,ignition negative pressure6000 pa,sintering negative pressure 10000 pa,material layer height 700 mm,moisture9-11%.Bentonite is used as binder.In the experiment,4% addition can strengthen the granulation effect of South African chromium ore powder,improve the permeability of the bed,optimize the sintering process index.The maximum utilization coefficient in laboratory is 0.56t/platform.h,and the ratio of bentonite in industrial production is appropriately increased to 6%.After sintering process,chromium ore is reduced to varying degrees.Metal chromium exists in sinter.The reduction degree of chromium ore is between 13.76% and 24.88%.The production practice of electric furnace shows that the slag with high Mg2+ or Mg O/Al2O3 is easy to produce strong crystallization when the temperature drops to about 1600 ℃,and the alloy particles are mixed in the slag too late to sink,which leads to the decrease of metal recovery.Through practical exploration,the Mg O/Al2O3 control in our company is the most suitable.In the smelting process,the recovery rate in the early stage of smelting increased rapidly,but after entering the refining period,the recovery rate decreased rapidly.The sinter and ball pressing ball in single furnace smelting time were controlled within 140 min,and the ball pressing ball was controlled within 160 min.The theoretical slag temperature is 170.At 0℃,the superheat degree of the control slag is optimal at 120-150℃.更多还原