摘要
近年来,赤铁矿选矿技术发展很快,以阴离子反浮选为核心的联合流程已经成为赤铁矿选矿的主流。但对阴离子反浮选体系中药剂作用机理的研究还不够完善,同时该工艺中使用的铁矿物抑制剂玉米淀粉还存在着明显的缺点,如配制复杂,须在85℃温度热水中配置,因而能耗高,以及对细颗粒抑制效果差造成尾矿品位偏高等。因而开展阴离子反浮选体系中药剂作用机理和铁矿物抑制剂的优化研究,对于完善阴离子反浮选工艺,提高工艺指标具有重要意义。
本文研究了油酸钠体系中几种抑制剂在矿物表面的作用机理以及对赤铁矿和石英浮选行为的影响规律,系统考察了赤铁矿和石英的可浮性、抑制剂对赤铁矿浮选行为的影响、Ca2+对矿物可浮性的影响、抑制剂对Ca2+作用后矿物可浮性的影响规律,利用动电位测定和红外光谱检测结果分析了抑制剂的作用机理,探讨了淀粉类抑制剂的絮凝特性和抑制特性之间的关系。
本论文对玉米淀粉、1#淀粉、糯玉米淀粉、糊精、磷酸酯化淀粉五种淀粉类铁矿物抑制剂进行了比较与分析。浮选试验结果表明：针对人工混合矿,浮选赤铁矿的回收率在95%时,精矿品位由高到低的次序为：糊精、玉米淀粉、糯玉米淀粉、1”淀粉和磷酸酯化淀粉。实际矿石浮选精矿的回收率在91.5%时,精矿品位由高到低的次序为：糊精、玉米淀粉、糯玉米淀粉、1#淀粉和磷酸酯化淀粉。人工混合矿和实际矿石的浮选结果一致。在赤铁矿和石英的分选过程中,淀粉是一种非选择性絮凝剂,絮凝作用主要是氢键作用引起的,絮凝作用越好选择性越差。
新型抑制剂1“淀粉在保持良好指标的分选前提下,具有在常温下用冷水配制成稳定溶液的优点。研究采用一次粗选一次精选三次扫选的阴离子反浮选工艺。玉米淀粉作抑制剂时,通过试验得到适宜的分选条件为：捕收剂油酸钠用量150g/t,活化剂氧化钙用量500g/t,抑制剂玉米淀粉用量800g/t,矿浆温度35℃,矿浆pH值11.75。1#淀粉作为新型抑制剂的适宜分选条件为：捕收剂油酸钠用量150g/t,活化剂氧化钙用量600g/t,新型抑制剂用量600g/t,矿浆温度35℃,矿浆pH值11.75。
玉米淀粉作为抑制剂在其最适宜的条件下,获得的精矿品位为64.26%,金属回收率88.43%,尾矿品位17.74%。新型抑制剂1”淀粉在其最适宜的条件下,获得的精矿品位为63.53%,回收率89.15%,尾矿品位16.78%。新型抑制剂1#淀粉与玉米淀粉作为抑制剂的分选效果接近,但新型抑制剂可以用冷水配制成稳定的溶液。
研究表明：pH值在10到12.5的区间内,各类淀粉对赤铁矿都有很强的抑制作用,抑制机理是淀粉中的羟基氧和赤铁矿表面裸露的铁元素发生了化学键合。pH值在11.5到12.5的区间内,各类淀粉对石英都有微弱的抑制作用,其作用机理是静电作用和氢键作用。pH在8到13的区间内,Ca2+对石英具有明显的活化作用,作用机理是吸附在矿物表面的Ca2+和CaOH+与油酸根离子发生化学作用而使石英疏水性增大。因此在油酸体系中,pH值在11.5到12.5的区间内,赤铁矿和石英存在最大的浮游差,是二者分离的理想条件。影响淀粉抑制作用的因素包括淀粉的链长、淀粉的直链和支链结构的含量、淀粉中的杂质、变性淀粉中引入基团的种类及基团取代度的大小
本研究成果对提高鞍山式赤铁矿资源的分选效率,降低选矿成本,具有重要的指导意义。
The mineral processing technology of hematite has been developed in a rapid speed in recent years. And the combined flowsheet at the core of anionic reverse flotation has become a mainstream of beneficiation for hematite. Excellent industrial performance can be obtained by employing corn starch as the depressant of iron minerals. However, it still has some disadvantages with coin starch as depressant such as complicated preparation, high energy consumption and high tailing grade. Therefore, further research on finding new depressant of iron minerals not only can meet the need of industrial production of mineral processing but also can improve the sustainable development of our steel industry.
Starch1#as a new depressant of iron minerals has been investigated in this paper. This depressant can be prepared to form stable solution by cold water in room temperature. In this way can the energy consumption be reduced compared with preparation of corn starch in hot water at the temperature of85℃.
Corn starch, starch1#, glutinous corn starch, dextrin and phosphate starch were investigated as depressants of iron minerals in this paper. The mechanism of these depressants on mineral surfaces and the effect of these depressants on the flotation behavior of hematite and quartz in sodium oleate system were studied. Simultaneously The flotability of hematite and quartz, the effect of depressants on flotation behavior of hematite, the effect of Ca2+on mineral flotability and the effect of Ca2+reacted with depressants on mineral flotability were employed. Furthermore, Zeta potential and FTIR were tested to analyze the mechanism of depressants. In addition, the relationship of flocculent characteristic with inhibitive characteristic was discussed for starch depressants.
The results showed that when the recovery of hematite flotation is95%for manual combined minerals, the concentrate grade follows a descending order as dextrin, corn starch, glutinous corn starch, starch1#and phosphate starch. When the recovery of hematite flotation reaches91.5%for practical minerals, the concentrate grade follows the same order as that for manual combined minerals. During the benefication process of hematite and quartz, starch is a non-selective flocculant. The flocculation is mainly caused by hydrogen bonding. The better the flocculation is, the worse the selectivity is.
Reverse flotation technology was adopted with primary rougher, primary cleaner and tertiary scavenger. With corn starch as depressant the optimal conditions are obtained as follow:
Sodium oleate dosage is150g/t,.calcium oxide dosage is500g/t, corn starch dosage is800g/t, slurry temperature is35℃and pH value of slurry is11.75. Meanwhile the optimal technological conditions with starch1#as new depressant are sodium oleate dosage15Og/t,.calcium oxide dosage600g/t, starch1#dosage600g/t, slurry temperature35℃and pH value of slurry11.75.
Under the optimal conditions with corn starch as depressant,64.26%concentrate grade,88.43%metal recovery and17.74%tailing grade are obtained. As compared,63.53%concentrate grade,80.15%metal recovery and16.78%tailing grade are obtained under the optimal conditions with starch1#as new depressant. Although the benefication performance of starch1#is the same as that of corn starch, starch1#can be prepared by cold water to form stable and uniform solution.
The research results indicated that when the pH value is between10and12.5, all starches play strong inhibitive roles on hematite. The inhibitive mechanism is the chemical bonding reaction between hydroxyl oxygen of starch and iron element on the naked hematite surface. When the pH value is between11.5and12.5, all starches show weak inhibitive effects on quartz, the mechanism of which is electrostatic and hydrogen bonding interaction. When the pH value is between8and13, Ca2+show an extraordinary activating interaction, the mechanism of which is that chemical reaction happened between the Ca2+and CaOH+adsorbed on the mineral surfaces and the oleate ions. Therefore, when pH value is between11.5and12.5in oleate system, there exists big flotability difference between hematite and quartz, which can lead to the ideal separation of them. The factors that influence inhibition of starch include the chain length of starch, the content of straight and branched chain of starch, impurities of starch and group species and group substitution degree introduced in modified starch.
The research results play a guidance role on improvement of the benefication efficiency of Anshan hematite resources and cost reduction.
引文
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