Assessment of possibility for safe mining of resources at Arcelor Mittal Temirtau's Zapadniy Karazhal mine by the numerical simulation methods

摘要

The Zapadniy Karazhal iron and manganese deposit is located in the Zhana-Arkaadministrative district of Karaganda region of the Republic of Kazakhstan, 270 kmsouthwest of Karaganda. The deposit has a sub-latitudinal strike and is hosted within atectonically complex zone. The main iron ore minerals are haematite, magnetite-haematite,and magnetite.The total length of the iron ore horizon is 5.5 km along strike and 1.7 km down dip. Theorebody dips at over 40° towards the south, but the dip is flatter in some zones, almostapproaching zero.The total thickness of the rock massif overlying the orebody is 386 m. The hangingwalland footwall if the orebody are composed mainly of limestone and other sedimentary rocks.The ore bedding is represented by alternating strata of iron and manganese ores,separated by limestone bands. The ore sequence includes from one to four iron ore unitsand from two to five manganese ore units. The main Fe3 unit comprises 65% of the volumeof the bedding. Iron grades vary from 25 to 66%, and manganese grades are from 5 to 45%.Most of the mining activity is conducted on the steeply dipping flank of the bedding(across strike). Recently, mining activities have been conducted in the flatter zones of theorebody. These zones are complicated by folding (both along and across strike).The hydrogeological conditions of the deposit are characterized by the structuralcomplexity, and three aquifers are present. Mine working development is thereforepreceded by advance drilling to avoid any possible water inrush into active mine workings.The Zapadniy Karazhal mine utilizes the horizon-room-and-pillar mining method formining of the iron ore resources. Each mining horizon is divided into blocks that consist ofcompensation (primary) stopes with horizontal dimensions of 20 m x 40 m and 45 mheight, separated by 15-17 m long safety pillars (SPs).The blocks are separated by inter-block gaps. The haulage level is prepared at thebottom of a pillar. This horizon consists of a network of scraper crosscuts 2 m in width,which receive the ore via ramps approximately 6 m in length. These ramps are connected(with the exit) to the conditional bottom of the stope. The sill pillars, approximately 12.5 min height, separate the mining horizon from the overlying horizon. The sill and interchamberpillars completely surround and isolate the stope from any waste rock failure.