Water-Soluble Polymer Depressants in Froth Flotation

从矿石中提取金属需要将矿石中的含金属矿物分离并提炼成单独的矿物精矿。今天的大多数矿物分离是通过泡沫浮选完成的，这种浮选根据矿物的表面疏水性来分离矿物。疏水性矿物(如油滴)漂浮到浓缩物中，而亲水性矿物则留在水中。然而，当亲水性矿物的粒度很小(~10微米)时，它们会被夹带到精矿中，从而降低了分选效率。此外，许多有毒的无机试剂，如氰化钠、重铬酸钾等，被用来将贱金属矿物分离成单独的精矿。解决这两个问题的一个潜在有效的解决方案是使用聚合物抑制剂，它的毒性很低或没有毒性，而且还可以增加颗粒尺寸，从而恢复分选效率。聚合物试剂的关键要求之一是对某些矿物有选择性地作用，而不是对矿石中的所有矿物起作用。这可以通过在聚合物中加入不同的官能团来实现。对聚合物试剂的另一个要求是它们是良好的絮凝剂。我们最近观察到，后者似乎取决于聚合物溶液的制备方式。关于聚合物溶液的制备及其絮凝性能，文献中存在相互矛盾的信息。拟议的项目旨在解决这两个问题。它包括两个子项目：(1)壳聚糖与磷酸盐或黄药基团的接枝；(2)聚合物溶液老化对聚合物絮凝活性的影响。这项研究成果将使加拿大受益，因为从矿产资源中提取金属是加拿大经济的主要贡献之一。

Metal extraction from ores requires that the metal-bearing minerals in the ores be separated and upgraded into individual mineral concentrates. Most of the mineral separation today is done by froth flotation, which separates minerals based on their surface hydrophobicity. Hydrophobic minerals are floated (like oil drops) to a concentrate while hydrophilic minerals stay in water. However, when the particle sizes of the hydrophilic minerals are very small (<~10 micron), they can be carried to the concentrate by entrainment, lowering separation efficiency. Also, many toxic inorganic reagents such as sodium cyanide, potassium dichromate, etc., are used to separate base metal minerals into individual concentrates. A potentially effective solution to counter both problems is to use polymer depressants, which have low or no toxicity and can also increase particle size, thus restore separation efficiency.One of the key requirements for the polymer reagents is that they selectively act on some minerals but not on all minerals in the ore. This can be achieved by incorporating different functional groups in the polymers. The other requirement for the polymer reagents is that they are good flocculants. We recently observed that the latter seems to depend on how the polymer solution is prepared. Literature contains contradictory information on polymer solution preparation and its flocculation performance. The proposed project is aimed at addressing these two issues. It contains two sub-projects: (1) grafting chitosan with phosphate or xanthate groups, (2) effect of ageing of polymer solutions on the flocculation activity of the polymers. The research results will benefit Canada as metal extraction from mineral resources is one of the major contributors to Canadian economy.