The effect of preliminary reagent treatment of marble rubble on the screening efficiency

Introduction. The high decorative properties and durability of marble determine its wide application in many areas of construction. Natural marble with fracturing is developed for the production of crushed stone of various fractions and micro calcite. The quality of the resulting commercial crushed stone is largely determined by screening operations. One of the quality characteristics is the content of pulverized and clay particles, which reduce the ability of the material to adhere to the binder. Dry screening often fails to achieve the required quality, and the use of wet screening increases the cost of the product. Difficulties with the separation of pulverized and clay particles are caused by the phenomena of particle agglomeration and their adhesion to large particles. In the process of grinding cement, additives of surfactants successfully combat the same phenomenon. The object of research is the process of dry screening of marble rubble. The subject of research is the parameters of dry screening of marble rubble, which reduce contamination of the surface of marble rubble particles with adhering dusty and clay particles and affect the screening efficiency. The purpose of the work is to study the possibility of increasing the dry screening of marble rubble (efficiency and productivity) using reagents that affect the agglomeration of small particles and their adhesion to the surface of large particles. The novelty of the research lies in the use of reagent treatment in the dry screening process and the study of the effect of reagent consumption and processing time on the granulometric composition, the state of the particle surface and the quality of the super lattice product. Based on the electrostatic components of the nature of the adhesion of small particles to large ones and the mechanism of action of the reagent, it is proposed to use the term “Athystatic” for the reagent. Result. Pretreatment of marble rubble with a solution of the DARAGRIND 240 reagent with a concentration of 0.1% at a flow rate of 5 g/t, which ensures moisture content of the material of no more than 5%, leads to an increase in the number of grains smaller than 2.5 mm from 8.3 to 19.1% due to the destruction of aggregates of small particles and preventing them from sticking to the surface of large particles, which is confirmed by the results of microscopic examination surfaces of crushed stone particles. With the established optimal parameters of reagent treatment, an increase in the efficiency of dry screening from 67.0 to 87.4% and an improvement in the chemical composition of crushed stone were achieved.