OPERATION FOCUS
Over the years the reliability and robustness of its longwall shearers has seen the fleet at Belaruskali reach over 90 machines , mainly SL300 models ( up to 2 m seam heights ) which account for over 80 % of the fleet , but also SL500 models for cutting the thicker seams of up to 3.2 m as well as low seam height SL300NE shearers for production in seam heights of up to 1.1 m . The company has dedicated a lot of investment to its success at Belaruskali in terms of customised solutions and has worked closely with the mine to also develop some new mining innovations such as double layer face mining using the SL300S and SL500S shearers , where S stands for selective mining . The double layer
method involves the use of a sliding door in the AFC whereby the waste halite between the two potash seams can be diverted to the void behind the shield while it is being cut . This method is specifically used in areas where the halite waste layer becomes thicker – in places it is 1 m or above . The first potash layer is cut and sent onto the conveyor / main gate and onto the skips for hoisting ; then the AFC changes direction and the salt / clay is sent to the goff behind the shields via the mentioned AFC door , before the conveyor direction is switched again and the second potash seam is cut . The waste conveyor also uses a centrifugal rotary blaster to blow the salt into the goff . Selective mining has mainly been used in Mine No 2 and Mine No 3 .
Belaruskali has also set some impressive longwall production records . In 2015 an Eickhoff SL300 shearer in Mine No 5 managed to produce 1 Mt in only eight months . The company has also deployed an innovative continuous miner at the complex ( see detailed section below ).
Overcoming challenges with continuous miner
IM visited the Eickhoff continuous miner in Mine
No 4 which was carrying out development . This mine was first commissioned in 1978 and the machine was working at the second mining
View from the cab of the Eickhoff CM2B-30P 2 plus close up of the cutting area
level , 440 m below surface but 600 m below sea level . There is another production level below this at 670 m below surface or 810 m below sea level . The visit required a 7 km lateral journey from the shaft station to the working area of the CM in a 20 km / h personnel carrier .
The continuous miner is being used for production and development and is utilised in this area as it is geologically difficult with several faults meaning it is not suitable for longwall production . The CM loads potash into a 17 t VS-17 shuttle car supplied by local company Niva Holding , which is actually based in Soligorsk near the mine , and also makes its own continuous miners ( the Cobra K6 , for 1.7 to 2 m seams ), powered roof supports , scraper face conveyors , pump stations and other equipment . A second locally-based company , JSC Soligorsk Institute of Resources Saving Problems with Pilot Productions ( SIPR ), also produces powered roof supports as well as tunnelling combines , with both companies having grown as the mining complex has developed . The SIPR combines of model KPR-3 are used to cut the main longwall headings and development gates . Roadheaders are also used for development . In the past the mine has also used Kopeysk Ural combines from Russia but these have been phased out .
A centrally positioned chain on the Eickhoff continuous potash miner allows complete cutting of the potash face ; in contrast to coal mining CMs , where the drum actually cuts in three parts of the drum , with the coal in between allowed to collapse . It isn ’ t possible to make one complete single piece cutting drum as it is driven by two gearboxes , but the central chain solution allows cutting right across the drum .
The Eickhoff machine was delivered in 2013 and is a 586 kW specialised machine for Belaruskali designated with the model name CM2B-30P 2 . This machine has 2 x 180 kW cutting motors , 1 x 125 kW motor for hydraulics and 2 x 45 kW motors for driving the conveyor ; as well as 2 x 5.5 kW auxiliary motors for the ventilation system . It loads the Niva shuttle car , which loads a Niva feeder ( or ‘ transfer bunker ’) which itself loads a conveyor , which in turn loads the main conveyor , mixing the potash mined by the CM with the longwall production . Crushing is carried out on surface after the ore is hoisted out in skips . The distance from the CM to the shuttle car varies from 200-300 m , with the shuttle car getting closer to the CM as it advances . Due to stresses in the drift headings , the CM production areas always have bolted roofs , with the mine currently using electricallypowered manual bolters . The CM is producing around 200-300 t every six hours in the mine due to the geological conditions but it capable of much more than this in trouble free mining areas .
Eickhoff told IM that the machine at Belaruskali is still classed as a pilot machine , designed for special conditions , though there is potential for more machines to be supplied to Belaruskali and to the wider potash mining industry . Effectively the company took a coal mining CM and made a number of adaptations to perfect it for potash mining . The company told IM : “ We are continually making improvements to the machine design to make it 100 % suited to the potash mining environment , where for example you cannot have free water . This has included rebuilding the ventilation system instead of using a water spray , and making software changes . It has also meant developing a closed water system for cooling .”
The cutting cycle sees the machine cut up into the potash first , then down before advancing . It sumps in at the top before shearing down . The Eickhoff machine is capable of cutting 3 m but in this application it cuts from a minimum of 2 m up to 2.4 m . The cutting width is 3.4 m but can be altered to 3 m if needed . The potash is mined in two main layers at Belaruskali , an upper thick layer of up to 2.5 m mined using standard Eickhoff longwall
AUGUST 2017 | International Mining