USING PICKLING SLUDGES OF HARDWARE PRODUCTION FOR MAKING CEMENTING MATERIALS

Abstract

Problem. There is a problem of utilization of pickling sludges of hardware production. The presence of hazardous wastes of the mentioned sludges causes probability of ecological contamination of soil and atmosphere. The analysis of the known technologies of sludge utilization specifies to their complication, unprofitability and costliness in connection with the necessity of high degree of cleaning and considerable power consumption. The task is to find more rational sludge processing technologies and create a possibility of its extensive application in construction materials industry. Goal. The aim is to solve the task of making alabaster binding materials by adding to the charge water-free dense deposits of the sludges of hardware production, and to reduce power consumption of gypsum production process. Methodology. A number of methods have been used for dehydration of pickling sludges, their drying, increasing sludge density by autoclaving air and steam, producing gypsum by adding to the charge 5 –25 % of sludges with the crystals of oxide iron (ІІ, ІІІ), durability testing of gypsum and determination of possible sludge content in the charge. The pickling sludges that contain 35–40 % of calcium sulfate and 28 % of iron sulfate are used. Results. The technological process for producing gypsum of the first and second class using the sludges of the etching room of plant «Dniprometyz» has been worked out. Originality. The technology for cake preparation is improved by using high density sludge of hardware production. The filter-press has been additionally equipped with the distribution device for the supply of air and steam. Crystalline compound of oxide iron (ІІ, ІІІ) that improves the coalescence with the gypsum in the process of its production has been obtained. Practical value. The technology of making high density cakes of pickling sludges of hardware production is offered. The models and parameters for gypsum production as well as the factors affecting durability of gypsum have been determined. The possibility for wider application of pickling sludges and substantial reduction of environmental pollution is created.