Optimisation of nickel-molybdenum ore beneficiation process

Nickel-molybdenum ore is difficult to be effectively separated by traditional beneficiation process due to the characteristics of high carbon, high silica and fine mineral embedded particle size. Based on the beneficiation research of a nickel-molybdenum ore (0.52% nickel, 0.74% molybdenum), this paper systematically discusses the direction of process optimisation and key parameter control, which can provide a reference for the efficient development of similar ores.

First. Ore characteristics and beneficiation difficulties

Nickel-molybdenum ore is in black plate or block shape, with fine mineral particles (about 10μm), closely coexisting with pyrite, which is difficult to dissociate. The content of SiO₂ in the ore reaches 35%, total carbon 7.3%, sulfur 7.5%, and nickel and molybdenum mainly exist in the sulfide state (72.98% nickel, 75.24% molybdenum). High silicon, high carbon and complex associated relations lead to poor flotation selectivity, and secondary mud easily interferes with the separation efficiency.

Second, Beneficiation process

Beneficiation process includes crushing→grinding→demudging and decarburisation→flotation→refining, the core links are as follows:

Crushing and grinding

The ore enters the grinding stage after coarse crushing and fine crushing, and the target fineness -0.075mm accounts for 82%. Tests show that too fine grinding (e.g. -0.075mm accounts for 88%) will exacerbate secondary mud generation and reduce the concentrate grade; insufficient fineness will result in insufficient mineral dissociation and reduced recovery.

Desliming and decarburisation pretreatment

Spiral chute re-election is used to preferentially remove carbon and mud. Comparing the effect of desliming by flotation and desliming by re-election, the decarbonisation rate of spiral chute process reaches 6.48%~4.72%, and the loss rate of nickel and molybdenum in the tailings is significantly lower than that of direct flotation, which creates a clean slurry environment for the subsequent flotation.

Optimisation of flotation conditions

Selection of capture agent: emulsified paraffin (100g/t) has the best capture capacity for nickel and molybdenum, and the grade of nickel in crude concentrate reaches 3.25% and molybdenum 1.05%.

Inhibitor application: phosphated CMC (30g/t) can effectively inhibit silica sludge, reduce the suspended matter of tailings, and acidified water glass (1000g/t) effect is comparable but the dosage is reduced by 97%.

Activator control: copper sulphate (200g/t) activates nickel minerals, the recovery rate increased to 81.22% of the peak, but the excessive addition of cost and grade decline.

Closed-circuit experiments and results

The results of the closed-circuit experiments through the combined process of ‘sludge removal and decarbonisation by re-election→copper flotation→nickel flotation’ show the following:

Copper concentrate: copper grade 6.58%, nickel 1.86%, copper recovery rate of more than 70%;

Nickel concentrate: nickel grade 4.21%, molybdenum recovery rate of 72.55%;

Comprehensive recovery: 81.22% nickel, 72.55% molybdenum, 85% vein rejection.

The process significantly reduces the smelting cost, and the nickel concentrate can be directly used in wet or fire smelting, with improved resource utilisation efficiency.

Conclusion and Prospect

In this study, efficient sorting of nickel-molybdenum ore was achieved by optimising the grinding fineness, desliming and decarburisation methods and flotation chemicals system. Future directions include:

Green pharmaceutical development: reduce the environmental risks of pharmaceuticals such as phosphate CMC;

Intelligent control: introducing online monitoring technology to dynamically adjust grinding and flotation parameters;

Process coupling: combining bioleaching or oxidation roasting to treat difficult-to-dissociate minerals.

As the demand for nickel and molybdenum resources grows, continuous innovation in mineral processing will provide technical support for the green and efficient development of complex ores.