Iron removal stations’ sludges postprocessing for its resource potential identification

Introduction. The sludge of the washing waters of the underground water iron removal station is a large-tonnage technogenic waste that is dangerous for the environment. The homogeneous chemical composition and finely dispersed structure of the sludge make it possible to consider it as a valuable raw material for the production of various products in the conditions of a forward movement towards a circular economy. Obtaining nanosized metal powders from the sludge of iron removal stations has a number of advantages over traditional physical, chemical and mechanical methods. To optimize the process of obtaining highly dispersed metal powders from the sludge of iron removal stations, it is necessary to study the influence of the main technological parameters on the size, shape and chemical composition of the final material. Materials and methods. Thermal treatment of the sludge of the iron removal station in the carbon monoxide medium was carried out in the temperature range of 400–600 °C. Ultrasonic dispersion was used to get an idea of the true particle size. The granulometric composition of the sludge was studied by electron microscopy and laser beam scattering. Results. The results of experimental studies of the granulometric composition of the treated sludge of iron removal stations are presented. The particles obtained at a temperature of 450 °C had the most pronounced spherical shape, low open porosity, and a low degree of adhesion to neighboring particles. These properties are key for micro- and nanopowder-based products. An increase in the temperature of sludge processing led to the adhesion of particles and their fusion into large aggregates with a brittle structure as a result of the development of crystallization processes. Conclusions. The proposed methods of physicochemical treatment in an environment of carbon monoxide and ultrasonic action of the sludge of an iron removal station, which is currently a technogenic waste, makes it possible to obtain a highly dispersed metal powder. This material has the necessary properties for use in modern high-tech industries.