OPERATION FOCUS
The CM loads a locally made shuttle car from Niva Holding
shearers , and a bottom layer up to 80 cm thick mined using Eickhoff low seam height shearers . However , the seam thicknesses do vary . Where the CM is being used , on average 2.2 m of material is cut , including the small amount of waste interburden , which is generally rock salt ( halite ) with some thin clay layers .
The geological issues are widespread in the mine , so there are plenty of potential
application areas for the machine . It does not have to advance on a flat surface , and a laser is used to follow the direction of the potash based on the mine plan , with the operator monitoring the angle of inclination . The operator usually sits in the cab following the production on screen . He also has a remote control rig for use in unstable areas as well as when the CM is moving from one working area to another , when he can remotely reverse tram the machine . The CM production advance is mainly limited by the maximum tramming distance of the shuttle car with its trailing 660 v cable . The CM itself requires a higher powered cable , at 1,140 v .
IM had travelled to the production area with Igor Novik , the Belaruskali Foreman responsible for the CM project , and asked him about his opinion of the Eickhoff machine : “ Despite the geological problems such as faults in the areas where it has been working , as well as interruptions in production at times due to economics such as falling potash prices , the CM has been working for us now for 3.5 years in a very stable way and we are quite happy with its performance . The machine is very well designed and reliable .”
He added : “ Eickhoff is always there to monitor the machine with us and work out any problems . All issues with spare parts and software have been solved very quickly and so from a service point of view we also hold Eickhoff in high regard . In a wider sense , Belaruskali wants to use the latest technology and equipment where possible to remain competitive . In addition to advanced mining equipment from Eickhoff we are also fortunate to have the local suppliers for shields , shuttle cars , feeders and other equipment .”
Belaruskali has tested a continuous miner from one of the local suppliers but was not able to achieve the same production with it ; and is still trying to make improvements to it .
Processing routes
The potash ores are the main raw material used to produce potash and compound fertilisers and other chemicals . The potash ore generally consists of sylvite ( KCl ), with waste halite ( NaCl ) containing inclusions of carnalite , anhydrite , silicate and carbonate ( insoluble residue ).
The basic method of processing of potash ores by hot leaching with further crystallisation of potash salt from saturated salt brines ( halurgical method ) began in the 19th century in Strasburg .
The primary methods of potash ore processing are flotation ( mechanical method ) and hot leaching ( chemical method ). JSC Belaruskali uses both methods : Production Units 1 , 2 and 3 process the potash ore by flotation and Production Unit 4 uses the hot leaching method .
The processing of ore by flotation is based on the different capacity of sylvite and halite surfaces to be moistened with water through the addition of specifically acting chemicals – surfactants – and further formation of the froth containing the valuable component . The production process includes the following stages :
■ Ore crushing and prescreening ;
■ Ore milling and presizing ;
■ Mechanical and flotation desliming of ore ;
■ Sylvite flotation ;
■ NaCl leaching from the flotation concentrate ;
■ Hydro-thickening and dehydration of tailings ;
■ Hydro-sizing and dehydration of
concentrate ;
■ Concentrate drying ;
■ Preparation of chemicals ;
■ Granulation of potassium chloride ;
■ Granule refining ;
■ Finished product loading ;
■ Waste stockpiling . The flotation method of ore processing is used to manufacture the reddish-pink standard and granular potassium chloride . The KCl mass fraction in the product is 95-96 %. The recovery of the valuable component when using the flotation method is 85.5-87.2 %.
The hot leaching method of ore processing is based on the physicochemical properties of NaCl-KCl-H 2O system . The main principle of this method is the different temperature-dependent degree of solubility of the mineral components – sylvite and halite : the high solubility of potassium chloride from ore by cycling the solution at 115 ° C and the further crystallisation of the valuable component on cooling .
The production process includes the following stages :
■ Ore crushing and prescreening ;
■ Leach heating ;
■ Ore dissolution ;
■ Filtration of halite tailings ;
■ Clarification of saturated leach ;
■ Crystallisation of potassium chloride ;
■ Thickening and centrifugation of potassium chloride slurry ;
■ Potassium chloride drying ;
■ Granulation of potassium chloride ;
■ Stockpiling , storage and loading ;
■ Recycled water cooling ;
■ Preparation of chemicals ;
■ Waste stockpiling
The hot leaching method is used to produce the white fine-crystalline and granular potassium chloride . The coarse crystalline product ( if necessary ) can be painted reddishpink . The KCl mass fraction in the product is 96- 99 %. The recovery of the valuable component of fertilisers produced when using the hot leaching method is 88-89 %. IM
The final production , in this case NPK fertiliser , is exported globally to over 90 countries
International Mining | AUGUST 2017