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美国矿山局的研究指出用内衬耐火砖的迴转窑直接加热离析铜矿石在技术上是可行的。过去离析过程只有在复杂得多的间接加热不锈钢迴转窑内才有效。该法是把粉矿与少量食盐和如焦炭之类的碳质物料预先混合,然后加热至830℃,生出细片状和薄膜状的金属铜吸附在焦炭颗粒上面。焙砂经冷却和细磨进行浮选回收铜。在直接加热离析过程中,必须在燃烧器内严格控制空气和煤气的混合。当燃烧天然气的过剩空气系数限制在1.15至1.20时,铜回收率才好。对含铜为1.4到6.2％的石英岩、石灰石岩、砂土岩和褐铁矿型的氧化铜矿的间断试验,结果得含铜为17至45％的浮选精矿,回收率为84至95％。炉气分析指出,因挥发损失的铜可忽略不计。直接加热离析的预备试验,后来用含1.4％Cu的石英岩矿石在处理能力约27公斤/小时的离析——浮选中间工厂的连续实验来补充。在一个典型实验中得含25％Cu的精选精矿,铜回收率84％。从工业观点来看,用内衬陶质物料的迴转窑将给过程以更大的吸引力,研究将继续进行以便创造好的离析条件。
A study by the US Bureau of Mines has concluded that it is technically feasible to heat and isolate copper ores directly from rotary kilns lined with refractory bricks. In the past, the segregation process was only effective in the much more complex indirectly heated stainless steel kilns. The method is the powder ore and a small amount of salt and carbonaceous materials such as coke and the like pre-mixed, and then heated to 830 ° C, resulting in fine flake and film-like metal copper adsorbed on the coke particles above. Calcined by cooling and fine grinding flotation recovery of copper. During direct heating and segregation, the mixture of air and gas must be tightly controlled within the burner. Copper recovery is good when the excess air factor for burning natural gas is limited to 1.15 to 1.20. An intermittent test of quartzite, limestone, sandstone and limonite type copper oxide containing 1.4 to 6.2% copper resulted in a flotation concentrate containing 17 to 45% copper with a recovery of 84 To 95%. Furnace gas analysis indicates that the loss of copper due to volatilization is negligible. Preliminary tests for direct thermal segregation were later supplemented by successive experiments with 1.4% Cu-bearing quartzite ore in an analytical separation-flotation plant having a capacity of about 27 kg / h. Concentrated concentrate containing 25% Cu in a typical experiment showed a copper recovery of 84%. From an industrial point of view, rotary kilns lined with pottery material will make the process more attractive and research will continue to create good separation conditions.