Phase transformation in suspension roasting of oolitic hematite ore

Suspension roasting followed by magnetic separation is a promising method to upgrade oolitic hematite ore.An oolitic hematite ore was roasted using suspension roasting technology at different temperatures.The phase transformation for iron minerals was investigated by XRD and Mossbauer spectrum,and the characteristics of roasted product were analyzed by VSM and SEM-EDS.Results indicate that the magnetic concentrate is of 58.73% Fe with iron recovery of 83.96% at 650 °C.The hematite is rapidly transformed into magnetite during the roasting with transformation ratio of 92.75% at 650 °C.Roasting temperature has a significant influence on the phase transformation of hematite to magnetite.The transformation ratio increases with increased temperature.After roasting,the magnetic susceptibility is significantly improved,while iron ore microstructure is not altered significantly.     

某鲕状赤铁矿流化床燃煤还原焙烧-磁选研究

运用小型循环流化床锅炉,针对铁品位为49.20%、磷质量分数为1.16%的湖北某鲕状赤铁矿进行磁化焙烧-磁选试验研究.试验结果表明,将粒径为106～150 μm的鲕状赤铁矿在700 ℃下焙烧15 min,选取磨矿后粒径在74 μm以下的颗粒质量分数为85%的焙烧矿物,运用湿式磁选管在139.22 kA/m的磁场强度下对筛选后的焙烧矿物进行磁选抛尾,可以获得铁品位为55.12%、全铁回收率为70.11%、磷质量分数为0.67%的铁精矿.研究表明,运用循环流化床局部还原性气氛高速磁化焙烧铁矿石是可行的,运用该磁化焙烧-磁选工艺流程可以达到一定的提铁降磷效果.     

鲕状赤铁矿磁化焙烧—磁选—反浮选降磷试验

鄂西宁乡式鲕状赤铁矿嵌布粒度极细,SiO2、Al2O3、P等杂质含量高,用其生产的铁精矿很难达到冶炼要求.针对铁品位为43.76%,磷含量为0.84%的鄂西鲕状赤铁矿进行提铁降磷试验研究,通过对磁化焙烧温度、磁化焙烧时间、还原煤的配比等影响因素的条件试验,确定在焙烧时间60 min,焙烧温度750℃,还原煤11%(质量比)的最佳焙烧条件.焙烧产品磨矿至-0.038 mm占80.54%、用永磁选机进行弱磁选,获得了铁品位54.10%、铁回收率93.19%、磷含量0.80%的粗铁精矿.进行反浮选药剂制度试验,得到了铁品位58.95%、铁综合回收率80%、磷含量0.50%的铁精矿,其最佳浮选药剂制度为NaOH 750 g/t,淀粉800 g/t,石灰500 g/t,RA-715 750 g/t,G310 107.73 g/t,浮选温度30℃.在此浮选制度下,进行一粗一精试验,精选石灰和捕收剂用量减半,可得铁品位59.87%,磷含量降至0.28%,综合回收率71.08%,综合试验结果表明,本文探索的工艺流程具有很大的可行性,能够为鲕状赤铁矿的选矿利用提供参考.     

Effect of bastnaesite as reductant on hematite reduction during in-situ suspension magnetization roasting of refractory iron ore under neutral atmosphereOA

The iron tailings of Bayan Obo mines are solid waste,which occupies land area and also causes environmental pollution;however,this waste can be recycled.In this study,based on the characteristics of iron minerals and fluorocarbonate contained in Bayan Obo iron tailings,clean magnetization roasting of iron minerals by bastnaesite from iron tailings during in-situ suspension magnetization roasting in a neutral atmosphere was explored.The results show that for iron tailings with a mass of 12 g, a N...     

焙烧对石煤钒矿孔结构的影响

分别采用BET法、BJH法和HK法测定了石煤原矿、石煤750℃焙烧渣、1 050℃焙烧渣3种样品的比表面积、中孔和微孔分布.结果表明,石煤原矿中主要以中孔为主,最可几孔径为4 nm,主要为墨水瓶状孔;750℃焙烧3 h,由于有机质氧化,原矿中微孔减少,中孔增加;1 050℃焙烧3 h,孔数量急剧减少,大量中孔和微孔消失,只有少量大孔,比表面积显著减小.     

助磨剂对鄂西高磷鲕状赤铁矿磨矿的影响

鄂西高磷鲕状赤铁矿在微细粒磨矿时黏度非常高,严重影响磨矿效率,导致磨矿能耗大幅上升。用助磨剂六偏磷酸钠和三聚磷酸钠对鄂西高磷鲕状赤铁矿进行降黏度磨矿试验。结果表明,添加两种助磨剂均可降低矿浆的黏度,助磨剂添加量为0.2%时降黏和助磨效果最佳;助磨剂使球磨机的生产能力得到显著提高,其相对增量最高可达144%,磨矿时间为5min时助磨效果最佳。添加助磨剂后磨矿产品中粒度小于38μm的颗粒含量明显增加,两种助磨剂都能有效降低磨矿的能耗,最大能耗降幅为57.14%。     

含钒页岩实验回转窑焙烧过程数值模拟

通过采用CFX软件,以实验回转窑内的气相场、颗粒相为研究对象,建立含钒页岩实验回转窑内焙烧过程的数值模拟模型,获得在正常的操作状态下窑内烟气温度场、流场、组分场、颗粒的运动轨迹的分布情况.计算结果显示,该窑内形成两个相对高温区,在焙烧带窑内的烟气及颗粒的运动速度增大,能较准确地反应窑内的焙烧过程,对研究开发高效的含钒页岩复合焙烧专用回转窑具有重要意义.     

Fragmentation mechanism of low-grade hematite ore in a high pressure grinding roll

The fragmentation mechanism of low-grade hematite ore in a high pressure grinding roll(HPGR) was studied based on the characteristics of comminuted products at different specific pressure levels. The major properties included the reduction ratio, liberation, specific surface energy, and specific surface area. The results showed that the fracture of low-grade hematite ore in HPGR was an interactive dynamic process in which the interaction between coarse particles of gangue minerals and fine particles of valuable minerals was alternately continuous with increased compactness and compacting strength of materials. Within a range of 2.8–4.4 N/mm~2, valuable minerals were crushed after preferentially absorbing energy, whereas gangue minerals were not completely crushed and only acted as an energy transfer medium. Within a range of 4.4–5.2 N/mm~2, gangue minerals were adequately crushed after absorbing the remaining energy, whereas preferentially crushed valuable minerals acted as an energy transfer medium. Within a range of 5.2–6.0 N/mm~2 range, the low-grade hematite ore was not further comminuted because of the "size effect" on the strength of materials, and the comminution effect of materials became stable.     

Carburization of ferrochromium metals in chromium ore fines containing coal during voluminal reduction by microwave heating

Chromium ore fines containing coal (COFCC) can be rapidly heated by microwave to conduct the voluminal reduction, which lays a foundation of getting sponge ferrochromium powders with a lower content of C. Under the conditions of COFCC with n(O):n(C) (molar ratio) as 1.00:0.84 and n(SiO₂):n(CaO) as 1.00:0.39, the samples were heated by 10 kW microwave power to reach the given temperatures and held for different times respectively. The results show that the low-C-Cr ferrochromium metal phase in the reduced materials forms before the high-C-Cr ferrochromium metal phase does. With increasing temperature the C content of ferrochromium metals is in a positive correlation with the content of Cr. The C content of ferrochromium metal in reduced materials is 0–10.07% with an average value of 4.68%. With the increase of holding time the Cr content in ferrochromium metals is in a negative correlation with the content of C, while the content of Fe changes in the contrary way. In the microwave field the kinetic conditions of carburization are closely related with the temperature of microwave heating, holding time and carbon fitting ratio. Foundation item: Project(50474083) supported by the National Natural Science Foundation of China; Project supported by the Baoshan Iron & Steel Co. Ltd. of China     

高磷铁矿碳热还原同步脱磷的实验研究

为探索高磷铁矿的有效利用途径,对高磷鲕状赤铁矿进行碳热还原同步脱磷实验研究,在含碳球团中添加CaO和Na2C O3作为脱磷剂,采用D T A-T G- M S综合热分析、X R D、SE M、E DS等方法分别对高磷鲕状赤铁矿的碳热还原过程以及还原产物进行分析. 结果表明,添加适量的CaO和Na2C O3可以显著提高脱磷率;在1 573 K、Na2C O3添加量为2 %、含碳球团碱度为1 .2的条件下,高磷鲕状赤铁矿能够被快速还原成含磷0 .09 %、含碳4 .6 %的碳饱和铁,脱磷率达到95 %;生铁中碳过饱和后以片状石墨的形态析出,生铁中的磷以夹杂物Ca3（P O4）2和Na2Ca4（P O4）2SiO4的形式存在     

煤矸砖隧道窑余热利用设备优化配置数值模拟研究

以某煤矿煤矸砖隧道窑余热回收利用系统为原型,建立了煤矸砖隧道窑余热回收利用系统的数学模型,研究了煤矸砖隧道窑内燃烧、传热过程,分析了余热回收利用设备分别放置在燃烧段、冷却段、燃烧段和冷却段连接处时隧道窑内的温度分布,模拟结果表明,取热设备的安装位置对隧道窑内温度分布,特别是对燃烧段温度有一定的影响,为保证矸砖烧制质量,应考虑取热设备安放位置对燃烧段矸砖温度的影响.     

An innovative process for direct reduction of cold-bound pellets from Iron concentrate with a coal-based rotary kiln

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Effect of Na<Subscript>2</Subscript>CO<Subscript>3</Subscript> and CaCO<Subscript>3</Subscript> on coreduction roasting of blast furnace dust and high-phosphorus oolitic hematite

Iron was recovered from blast furnace dust and high-phosphorus oolitic hematite in the presence of Na₂CO₃ and CaCO₃ additives. The functions of Na₂CO₃ and CaCO₃ during the coreduction roasting process were investigated by XRD and SEM-EDS analyses. Results indicate that these additives not only hinder the reduction of fluorapatite, CaCO₃ also decreases the P content of direct reduced iron (DRI) by increasing the reduction alkalinity. P remains as fluorapatite in the slag, which can be removed by grinding and magnetic separation under optimal conditions. The Na₂CO₃ promotes hematite reduction and improves the iron recovery (ε_Fe) by replacing the FeO from fayalite, which results in quick growth and aggregation of metallic iron and improvement of ε_Fe in DRI. A DRI with 91.88 mass% Fe, and 0.065 mass% P can be achieved at a recovery of 87.86 mass% under the optimal condition.     

鞍钢使用大比例赤铁矿生产氧化球团的研究

针对鞍山矿业大孤山球团厂生产氧化球团用磁铁矿不足的问题,进行了大比例赤铁矿生产氧化球团的实验室研究和半工业化链蓖机—回转窑生产试验．实验室研究结果表明,鞍千赤铁矿配比不超过40％时,球团矿抗压强度大于2500N／个,低温还原粉化指数RDI＋3.15大于82.05％,还原膨胀指数RSI小于15.02％,均能满足现代化大高炉生产的要求．工业试验表明,鞍千赤铁矿配比不超过40％时,生产稳定,产品质量全面满足鞍钢炼铁原料的技术要求．2011年进行了推广应用,生产实际结果表明,2011年比基准期增长创效4.2亿元．     

Investigation of stability of a tunnel in a deep coal mine in China

Stability level of tunnels that exist in an underground mine has a great influence on the safety, production and economic performance of mines. Ensuring of stability for soft-rock tunnels is an important task for deep coal mines located in high in situ stress conditions. Using the available information on stratigraphy, geological structures, in situ stress measurements and geo-mechanical properties of intact rock and discontinuity interfaces, a three-dimensional numerical model was built by using 3DEC software to simulate the stress conditions around a tunnel located under high in situ stress conditions in a coal rock mass in China. Analyses were conducted for several tunnel shapes and rock support patterns. Results obtained for the distribution of failure zones, and stress and displacement fields around the tunnel were compared to select the best tunnel shape and support pattern to achieve the optimum stability conditions.     

复吹转炉锰矿直接合金化热力学模型研究

基于某钢厂铁水、废钢和造渣料等的成分得出转炉炼钢的渣量计算模型,根据热力学原理得出锰的收得率和终点锰含量的预报模型。对模型研究结果表明,提高终点出钢温度、渣碱度、锰矿品位和铁水Mn含量,降低终渣含量及渣中FeO含量,可显著提高Mn的收得率和终点Mn含量。     

Effect of CO_2 and N_2 on microbial community changes during column bioleaching of low-grade high pyrite-bearing chalcocite ore

Simulated heap bioleaching of low-grade high pyrite-bearing chalcocite ore was conducted at 40 °C with aeration of CO_2 and N_2.Ore samples were collected at day 43,64,85,106 and subjected to microbial community analysis by 16S rRNA gene clone library.Phylogenetic analyses of 16S rDNA fragments revealed that the retrieved sequences are mainly related to genus Acidithiobacillus,Leptospirillum and Sulfobacillus.Aeration of CO_2 and N_2 significantly impacted the microbial community composition.When CO_2 was aerated,the proportion of genus Acidithiobacillus considerably increased,whereas the proportion of genus Leptospirillum and genus Sulfobacillus declined.However,with the aeration of N_2,the proportion of genus Acidithiobacillus and Leptospirillum increased,but genus Sulfobacillus decreased.When there was no aeration,the microbial community was similar to the inocula with the proportion of genus Leptospirillum mounted.These results indicated that the limitation of oxygen could change the bioleaching microbial community and the aeration of CO_2 and N_2 was favourable for the growth of sulfur-oxidizer(At.caldus) and iron-oxidizer(L.ferriphilum) respectively,which could be used for the regulation of microorganisms' role in mineral bioleaching.