Osypenko I. The use of pulverized waste from electrometallurgical industries to create metal-phosphate compositions of molding and core mixtures

Today, the reason for the limited use of phosphate cold –hardening mixtures (f-CHM) with phosphate salts and CHM with iron and magnesium-containing dust of technogenic origin (DTO) in foundries is difficult to control and multifactorial curing rate, significant shrinkage, scattering, brittleness at the initial stage of hardening and particle size distribution of DTO, high cost, the need for appropriate pre-treatment, which complicates the management of the process of structuring metal-phosphate СHM and reduces the quality of castings. The mineralogical, chemical, granulometric composition of highly dispersed secondary materials and wastes of electrometallurgical production manufactured in Ukraine is established in the work. It is determined that the level of physical and technological properties of f-CHM is influenced by the mass amount of crystalline chemically active compounds of DTO, as well as the value of dust dispersion. The mass content of chemically active compounds of DTO and its dispersion additively affect the level of properties of structured f-CHM. That is, the more chemically active crystalline compounds in the DTO and the larger the specific surface area of its surface, the higher its technological activity. According to the results of experimental studies, a number of technological activities of metal oxides in dusty materials of technogenic origin in relation to orthophosphoric acid with a specific surface area of dust from 1.81 to 22.00 m2/g and expanded a number of chemical activity compounds MnO, MnO2. The complex effect of the content of orthophosphoric acid and DTO at their ratio of 0.1… 10% and exposure of the mixture in air within 3 to 24 hours and the regularities of the complex effect of the content of DTO and orthophosphoric acid in the range from 1 to 10% by weight and concentration of orthophosphoric acid acid 60% on the properties of f-CHM. Optimized compositions of f-CHM with the addition of gas cleaning dust for ferrosilicon production (DGCFP), gas cleaning dust of normal fused electrocorundum (DGCNE) and DGCFP + DGCNE at a mass ratio of 1: 1 below the compressive strength, gas permeability and scattering after 3 and 24 hours. The functional dependence between the scattering of structured f-HTS with the addition of DGCFP from the time of their exposure to air, the value of gas permeability and compressive strength in the range from 1 to 24 hours. The developed warehouses of f-CHM with DTO were tested in foundries at several metallurgical enterprises of Ukraine in the manufacture of castings from high manganese steel. The practical value of the work is to develop optimal and rational compositions of f- CHM from DTO (DGCFP, DGCNE and their mixtures) with a given level of physical and technological properties.