Use of conditioning time to investigate the mechanisms of interactions of selected fatty acids on hematite Part II laboratory investigations

It is the aim of this paper to examine the effects of conditioning time on the flotation of hematite using three technical grade fatty acid reagents as providing additional evidence on their mechanism of interaction with the hematite surface. Various mechanisms have been postulated as occurring as conditioning time is increased. Both physical (e.g. conditioning time and power input) and chemical (nature, dispersion and solubility of the adsorbing species) contribute to the mechanisms of attachment of collector. In this paper, the mechanism of attachment of oleate to hematite can be readily explained by chemisorption, but the mechanism of attachment of lauric acid appears to be physical adsorption at neutral pH. The flotation of hematite with a mixture of tallow-type fatty acids (palmitic, stearic and oleic acids) is very sensitive to conditioning time, and suggests that, even though flotation is very effective at short conditioning times, it is very susceptible to the presence of fines and their associated high surface areas. It is therefore obvious that both the physical and chemical conditions contribute to the mechanisms of adsorption of fatty acids on iron-containing oxide minerals and must be understood in order to optimise the flotation of these minerals in an industrial situation.     

Changes in the structure of hematite by extended dry grinding in relation to imposed stress energy

The effect of extended dry milling in different mills on the structural changes of hematite concentrate has been investigated using a combination analysis of XRD line broadening, BET and particle size measurements. Structural changes were followed by XRD line broadening analysis using integral breadth method and Warren-Averbach approach. For analysis, the stress energy was estimated by considering different grinding variables in different mills and changes in the structure discussed in terms of stress energy.Within comparable range of stress energy, lower BET surface area was produced by grinding in the vibratory mill. The maximum surface area increased to 18,400 m²/kg in the vibratory mill after releasing 51,300 kJ/kg energy. The conversion of the 80% of initial hematite to amorphous phase during extended dry grinding by tumbling, planetary and vibratory mills, needs 4000, 8500 and 50,000 kJ/kg energy respectively. It was understood that vibratory mill introduces the minimum lattice strain and gives the largest crystallites when applying the same level of stress energy. The smallest crystallites with grinding in tumbling, vibratory and planetary mills were obtained about 17.3, 13.5 and 5.6 nm after releasing 5230, 51,300 and 15,600 kJ/kg respectively. For these levels of stress energy, in turn, the microstrain <ε_L=10 nm²>^1/2 exceeds 4.4 × 10^− 3, 3.9 × 10^− 3 and 5.3 × 10^− 3.It was further revealed that higher concentrations of defects (Amorphization and excess energy) per unit surface area were induced by grinding in the planetary and tumbling mills. A theoretical calculation of the energy contribution to the long-lived defects indicated that products from tumbling and planetary mills have higher excess energy compared to the products from vibratory mill for the same stress energy. The maximum theoretical excess energy was estimated about 75.4, 80.0 and 81.3 kJ per mole of the ground hematite with tumbling, vibratory and planetary mills after releasing 5230, 51,300 and 15,600 kJ/kg of stress energy respectively. Grinding in vibratory mill needs much more energy to reach the same effect as the other used mills. A comparison of specific energy input and stress energy among the used mills points out that for generation of the same levels of stress energy, the planetary mill consumes more energy than the other used mills.     

不同淀粉对混合磁选精矿抑制效果的研究

通过淀粉对赤铁矿的抑制机理分析,经过浮选试验,研究了玉米淀粉、糯玉米淀粉、马铃薯淀粉、木薯淀粉在齐大山铁矿选矿分厂浮选中的作用效果。研究结果表明,各种淀粉对赤铁矿都有一定的抑制作用,各种淀粉的的分子量不相同,支链部分和直链部分的比例不同,是淀粉对赤铁矿抑制作用存在差别的主要原因。     

某赤铁矿尾矿的综合利用

对赤铁矿尾矿采用酸浸—还原工艺,以达到固废资源化、减量化的目的。结果表明:在酸浸过程中,当反应温度为100℃、浸出时间为2.5h、搅拌转速为400 r/min、溶液硫酸浓度为45%、硫酸过量系数为1.5时,全铁回收率达82.3%。在还原过程中,在反应时间为2h、反应温度为50℃、铁屑的过量系数为1.4时,可以制得一等品绿矾产品。     

东鞍山含碳酸盐难选铁矿石分步浮选工艺研究

介绍了东鞍山烧结厂含碳酸盐难选铁矿石的工艺矿物学及浮选分离特性，提出了处理难选碳酸盐铁矿的浮选新工艺--分步浮选，即第一步在中性条件下采用正浮选分选菱铁矿；第二步在高pH值下采用反浮选分选赤铁矿。实验室闭路浮选试验结果表明，在浮选给矿品位为52.30% 时，采用分步浮选工艺可以获得铁品位 66.34%、回收率71.60%的铁精矿。     

用赤铁矿制备聚硅酸铁絮凝剂及应用研究

采用酸浸-催化氧化-水解-聚合工艺，进行了以低品位赤铁矿、废硫酸和硅酸钠为原料制备聚硅酸铁（PSF）絮凝剂的试验研究，结果表明，适宜的工艺条件为硫酸浓度5～6 mol/L，液固比4∶1，酸浸温度90 ℃，酸浸时间2～3 h，氧流量40 cm³/（min·L），Fe/Si摩尔比=2，硅酸活化pH值=3，硅酸活化时间25 min，陈化时间2 h。用所制备的PSF处理印染废水，并与聚合硫酸铁（PFS）和聚合氯化铝（PAC）进行比较，结果表明，在90 mg/L用量下，PSF可使废水中浊度、色度、SS和COD_Cr的去除率分别达到91.5%、87.8%、92.2%和78.5%，比相同用量下的PFS和PAC均分别高出10、24、14、18个百分点以上。     

湿式永磁强磁选机分选赤铁矿石试验研究

介绍了广义分选空间湿式永磁强磁选机结构及工作原理，采用该机对昆钢上厂铁矿王家滩矿区赤铁矿石进行了分选试验。试验研究表明，-6 mm原矿经广义分选空间湿式永磁强磁强磁选机一次粗选、一次扫选、一次精选分选，可获得铁精矿品位53.03%、回收率83.32%的技术指标，为解决王家滩矿区赤铁矿石分选提供了有效途径。     

新型捕收剂对赤铁矿捕收性能的研究

介绍了新型铁矿物捕收剂ＲＣ９５０２用于浮选包钢选厂一、三系列强磁铁精矿（α４０．０３％ＳＰｃ）中的有用铁矿物试验，经一次反浮、正浮、一次精选可使精矿品位提高到６３．９１％ＳＦｅ，回收率为６７．４４％，ＦＣ９５０２能有效地捕收赤褐铁矿和磁铁矿，与用氧化石腊皂作捕收剂比较，不仅能获得更好的选别指标，而且可降低捕收剂成本约３０％．     

磁种对赤铁矿铁矿石脱泥工艺的影响

在选择性絮凝分选过程中加入磁种，以增加絮团的磁化率，达到用磁选或磁选、重选联合方法分离絮团的目的。根据磁种在选择性絮凝－脱泥工艺分选赤铁矿中的作用试验结果，论述磁种用量、粒度对该工艺指标的影响。     

氟化物在硅铁分离中的应用及作用机理

包头白云鄂博矿床的选矿实践迫切地要求解决赤铁矿与含铁硅酸盐矿物分离这一难题。本文系统地考察了三类典型氟化物——氟化钠、氟氫酸及氟硅酸钠对赤铁矿和含铁硅酸盐矿物锥辉石浮游性的调整作用,讨论了分选的选择性及影响因素,成功地实现了赤铁矿和锥辉石的人工混合矿物及实际矿石的浮选分离。本文还对氟化物与矿物作用机理进行了探讨。