To improve the separation effect of mixed concentrates, it is often necessary to remove reagents from the mixed concentrates before separation. On the one hand, the collector film on the surface of the mixed concentrate needs to be removed, and on the other hand, excess reagents in the slurry need to be removed. Reagent removal methods can be divided into three categories: (1) Mechanical reagent removal methods, including regrinding, concentration, scrubbing, filtration and washing, and multiple cleaning. Regrinding of mixed concentrates mainly dissociates the intergrowth monomers in the mixed concentrates, and can also remove some reagents. When concentrating mixed concentrates, the reagents in the water can be removed by dehydration. Concentration can be achieved using a thickener or a hydrocyclone. Scrubbing removes some reagents by friction between mineral particles during strong stirring of the thick slurry, but this method is not suitable for minerals that are prone to mud formation. Filtration and washing involves concentrating and filtering the mixed concentrate, washing it with water on a filter press, and then re-floating the filter cake. This is the most thorough mechanical de-reagent method, but it is complex, costly, and rarely used. Multiple cleaning processes are both a process of improving the grade of the mixed concentrate and a de-reagent process. Generally, the pulp concentration decreases with each cleaning process, so some reagents can be removed through desorption, but the effect is limited.

(2) Desorption methods. One is sodium sulfide desorption, and the other is activated carbon desorption. Sodium sulfide can desorb the collector film of the sulfide ore mixed concentrate, resulting in more thorough de-reagent removal. However, a large amount of sodium sulfide is required, and after de-reagent removal, the concentrate must be concentrated and filtered to remove the remaining sodium sulfide; otherwise, the sulfide ore will be inhibited by the sodium sulfide. Activated carbon desorption can adsorb excess reagents in the pulp and promote the desorption of reagents from the mineral surface. This method is not as thorough as the sodium sulfide method, but it is convenient to use. (3) Heating and roasting methods. The heating method has been widely used in the separation of mixed concentrates. The roasting method has been used in the separation of copper-molybdenum mixed concentrates. Both of these methods are relatively expensive.