Pochtariov O. Improvement of technological means of quality management of iron ore raw materials in underground mining.

The need to maintain high quality indicators of iron ore raw materials in accordance with requirements of metallurgical production is an important problem inherent in production of marketable products in iron ore underground mining. The issue of maintaining high quality indicators of mined iron ore has become especially acute due to transition to mining deep levels, deterioration of mining and geological conditions of deposits, the lag in modern mining technologies, especially those of ore breaking and drawing. These factors lead to a decrease in the ratio of balance ore reserves extraction to 80-84% of mine block resources. In addition, dilution of the broken ore mass with waste rocks results in a 1.5-12% (abs.) decrease in the iron content compared to the initial iron content in the ore massif. Thus, improvement of the technology of underground mining of iron ores in order to manage the quality of marketable raw materials is an urgent scientific and technical task of great scientific and practical importance leading to improvement of underground mining efficiency and increase in the ratio of mineral extraction from the subsoil. The introduction contains a general description of the thesis, sets out the purpose and objectives of the research, and substantiates relevance, scientific novelty and practical value of the work. The first section of the work analyzes the current state of the raw material base of Kryvbas. It also analyzes and generalizes causes of high rates of ore losses and dilution in the conditions of iron ore underground mining in Kryvyi Rih basin. Based on the analysis conducted, it is determined that the quality of the iron ore raw material is the main indicator that ensures its competitiveness in the national and foreign markets. The second section of the work studies the impact of drilling and blasting on quality indicators of broken ore extraction from stoping blocks. It is established that the quality of ore fragmentation by blasting directly impacts the subsequent processes of the broken ore drawing and handling. Deviation of boreholes relative to the design contour is identified as a key cause of poor-quality ore fragmentation during drilling and blasting. The research conducted enables identification of main regularities of long borehole curving. It is found that the broken ore quality depends on the volume of a compensation space. The larger the compensation space is, the greater the amount of pure undiluted ore to be extracted from the block becomes. Based on the research conducted, a high triangular prism shape is proposed for the compensation room. The third section provides a study of the dependency of broken ore drawing and handling on the mined ore mass quality. The problem of reducing the volume of broken ore losses in the slow-moving “dead zone” of the deposit footwall is identified as one of the main factors impacting the ratio of ore extraction from stoping blocks. The innovative technology for extracting ore from the slow-moving “dead zone” of the deposit footwall is proposed. The technology is named drawing through “block collecting funnels”. The dependency of the amount of broken ore losses in the “dead zone” of the deposit footwall on the ore deposit dip and thickness is established for technologies involving formation of “block collecting funnels”. Designs of the bottom of the block with draw trenches with frontal ore loading when the loader bucket digging-in angle is 90º to the muckpile are developed and proposed. The fourth section presents the results of implementation of new highly efficient and environmentally friendly technologies for improving the quality of ore in the underground mining of iron ore deposits. Based on the latest experience and prospects for the future, it is concluded that basic innovative and unchallenged technological processes include ITmk3, FASTMET/FASTMELT and Midrex. The general conclusions summarize the work conducted and describe the main results obtained in the course the research. The thesis is supplemented with appendices containing acts of implementation of the research results and patents for inventions.