Study and development of hardening mixture composition based on unconventional industrial waste
Authors: Golik Vladimir I , Razorenov Iurii I. , Vagin Vladimir S. , Liashenko Vasilii I. 
Published: May 2021

Relevance. Phosphogypsum, the product of apatites chemical processing, is one of the most common mining wastes. Phosphogypsum utilization is not widespread yet, therefore its cost is low. Integrated research has been carried out to determine the technological capacity and economic feasibility of phosphogypsum, sludge, and dolomite utilization as binders in the conversion of ore production techniques. Research aim is to develop a hardening mixture composition based on unconventional industrial waste, determine the technological capacity and economic feasibility of utilizing phosphogypsum, sludge, dolomite, and other accessible low activity wastes as a substitute for expensive and relatively scarce binder material. Research methodology. Initial data are studied of the wastes possessing binding properties. The efficiency of admixing them is determined from the robustness of hardening backfill mixtures control samples that have been produced in laboratory conditions. Based on the research, a database is created to apply the results in practice for mining development. Results. The hardening materials compositions were obtained based on unconventional industrial waste including hydrometallurgical and dressing tailings, furnace clinker, low-grade sand, thermal power plants (TPP) and chemical industry ashes. The optimal composition of the mixture per cubic meter: tailings – 600–750 kg; TPP ash – 180–220 kg; cement dust – 250–315 kg; cement – 35–40 kg; tempering water – 450–515 l under the mixture’s fluidity of about 14 cm according to the readings of the mortar consistency measuring device (StroyTsNIL cone). To ensure radiation safety of the hardening mixture that is based on unconventional industrial waste, it is advisable to take into account not only their chemical and physical-mechanical indicators but the value of naturally radioactive nuclides’ effective activity as well. Conclusions. It has been stated that the robustness of mixtures containing gypsum is 1.5–2.0 times higher, and under the hardening time of 3, 6 and 12 months makes up 3.1; 5.7 and 7.6 MPa correspondingly. It has been shown that the compositions with the binder’s flow rate of 450 kg per cubic meter under the cement : sludge ratio of 1 : 2 show the robustness from 2.8 to 4.9 MPa in 28 days. The content of low-grade sand levigate particles reaches 20% and more. Classes with a specific area of 28.4 m2/kg refer to fine sand, and with a specific area of 27.7 m2/kg refer to medium sand. The robustness of the 28 days old composition reaches 0.5 MPa, 90 days – 0.9 MPa depending on the cement flow rate. It has been substantiated that binders based on fluorine gypsum, phosphogypsum, and belite sludge by mixed grinding of the granulated 26 "Izvestiya vysshikh uchebnykh zavedenii. Gornyi zhurnal". No. 3. 2021 ISSN 0536-1028 blast-furnace slug with the ferrochrome sludge and phosphogypsum up to 70%, 0.08 mm size, show the robustness of the binder up to 3.0 MPa with the flow rate of 450 kg per a cubic meter of the mixture. Keywords: industrial waste; hardening mixture; binder; PPT ash; ash and slag; cement; fluorine gypsum; phosphogypsum; non-reactive aggregate; belite sludge; naturally radioactive nuclides. Acknowledgements. Specialists from Platov South-Russian State Polytechnic University (Novocherkassk, Russia), Ukrainian Research and Design Institute of Industrial Technology (Zhovti Vody, Ukraine), Vostochnyy (Eastern) Mining and Enrichment Combine (Zhovti Vody, Ukraine), Dnipro University of Technology (Dnipro, Ukraine) and others took part in creating, improving, and introducing R&D.