Improving Nickel Recovery in Froth Flotation by Purifying Concentrators Process Water Using Dissolved Air Flotation

Abstract

The pressure for saving water by closing the water loops in mineral processing is increasing continuously. The drivers for higher recirculating rates include water scarcity in dry areas, environmental legislation that is becoming stricter in most countries, limitations set for wet tailings management and the increased demands for social licenses to operate. At the same time, to make mineral processing sustainable, the recovery of valuable minerals should be maximized. This leads for a need to close the process water circulation. To see the effect of closed water circulation on metallurgical performance, flotation tests were carried out with nickel concentrate thickener overflow water before and after the process of water purification by dissolved air flotation (DAF). Both total nickel recovery and concentrate grade in laboratory scale flotation tests to the Ni rougher-scavenger concentrate increased after DAF treatment. Chemical and mineralogical characterizations revealed that after DAF treatment, the process water contained fewer metal hydroxides and less fine-grained silicate mineral particles, which is most likely the reason for the improvement in the nickel flotation performance. Based on the feasibility study, improved nickel recovery by DAF treatment of process water can bring economic benefits at a concentrator plant.

Simulating the Impact of Ore and Water Quality on Flotation Recovery during the Life of a Mine

“…Furthermore, recycled and mine waters have higher conductivity than river and tailings waters, indicating that these water streams contain a higher level of impurities in general. The simulated results are in line with previous flotation tests, in which higher nickel recoveries were achieved with lower impurity levels in water [9].…”

“…The impact of water properties on flotation performance can be remarkable for some minerals, with one of the most sensitive ones being pentlandite ((Fe,Ni) 9 S 8 ), the main sulfide nickel mineral [9]. The impurities accumulating in the process may stem from raw water, originate from flotation reagents, or dissolve from the ore to the process water [10].…”