The main problem of preparing the components of the charge before mixing is maintaining the constancy of the specified characteristics over time. In practice, for high-quality pelletizing, deviations in the moisture content of the concentrate should not exceed 0.2%, specific surface area ±100cm2/gram, fractional composition 0.5% in absolute terms. Two parameters that allow you to quickly monitor and manage the state of the concentrate are the moisture content and fractional composition of the concentrate. Many enterprises install moisture analyzers of the concentrate, which promptly display the moisture content in the concentrate online and allow you to quickly manage the concentrate filtration process. In fact, the process of stabilizing the constancy of moisture is much more complicated than it seems in reality, since this is a multifactorial system and the influence on this criterion begins at the stage of ore mining in the quarry, its crushing and directly the enrichment technology itself. The preparation of other components of the charge (bentonite, limestone, solid fuel, return) does not cause any particular problems since the process of preparation (crushing, grinding with drying) of these materials is carried out directly at the pelletizing plant itself. In practice, two indicators are constantly monitored in the technological process: the fractional composition of the material and the moisture content. The specific surface of non-ferrous materials of the  charge is determined periodically and monitored by the research laboratory during experiments, significant violations of technology or commissioning work on the grinding equipment. 

     The preparation of the batch components (limestone, bentonite, return, solid fuel) can be performed either separately for each type of material or jointly for several materials. Solid fuel is ground together with another inert material, such as limestone or bentonite. This is especially important when the gas cleaning units of the mill paths contain electrostatic precipitators. With small volumes of the batch of fluxing and binding additives and in order to optimize costs, three materials are ground simultaneously (limestone, bentonite
and return) in one mill cycle. Since the return of fired pellets has strong abrasive properties, it is advisable to grind it with limestone or bentonite in order to reduce the wear of the volutes, fan rotors and gas duct systems of the mill paths. Organic additives are often used to reduce the consumption of bentonite, improve the shape and grain size distribution of raw pellets. They are delivered to the workshop already prepared in big bags and are dosed into the batch using screw feeders. Organic additives are very sensitive to moisture, including hygroscopic, therefore, to avoid the formation of lumps of material, they must be stored in closed polyethylene containers. When storing in intermediate or screw feeder bunkers, heating of these bunkers to a temperature of 25-300 C must be provided. Before the mixing operation, the procedure for dosing organic binders into the batch is as follows: concentrate → limestone (return) → organic binder → bentonite. 

     The chemical composition of materials is determined for all components of the charge to correctly perform the charge and obtain the required quality characteristics of the fired pellets in terms of basicity modulus and iron content. Dosing and mixing of the material must ensure the specified parameters for dosing accuracy (at least ±0.5%) and mixing coefficient (at least 90%). It is recommended to use vortex mixers "Lödige" or intensive mixers "Eirich" with a mixing coefficient of 90-95%. Rotary and drum mixers do not provide the required mixing quality, since the mixing coefficient is 60 and 75%, respectively.