The raw ore Tungsten is to be extracted from Sangdong mine. This mine is located North China-Korea border. The ore deposit are in contact with several minerals like tungsten, carbonate sedimentary rocks and calcium carbonate layers and molybdenum. A series of processes involving the heavy equipment and chemicals are used to extract the desired quantity of tungsten efficiently, effectively and economically.
To extract the tungsten ore, the process uses several major steps in the following order:
1. Primary Jaw and Secondary Cone Crusher
3. Rod and Ball mills
4. Sulphide and Tungsten Rougher and Scavenger Flotation
6. Filtration and Packing section
The Processing plant has a capacity of 1920 metric tons per day. The run of mine (ROM) ore will be fed at the feed hopper. The ROM ore will be at 600mm. The usage of the primary jaw crusher allows the ore to be broken into smaller pieces. In terms of size classification, a 19mm screener is used. The screener separates the ore sizes and the bigger ores then ends up in the secondary cone crusher. This cone crusher breaks the ore and recycles back to jaw crusher. This process is a closed loop. Ores that passes through the 19mm screener then go to a coarse ore stockpile. The stockpile is estimated to be 2000 tons. The ores are drawn from the stockpile and transferred to rod mill. The rod mill grinds and sends to cyclone cluster. The cyclone cluster is used to separate the ores into underflow and overflow. The underflow ores is transported to ball mill which grinds and reduce the size until a more uniform distribution is achieved. The particles are reduced to 75 microns and circulating load will be at 250%. The overflow from cyclone cluster ends up the sulphide flotation tank.
The purpose of the rougher and scavenger flotation is to segregate the valuable tungsten from other mineral particles. There are a total of 3 flotation process including of sulphide and tungsten. After the first separation from the sulphide flotation, the cleaner particles are transferred to thickener. A thickener is used to reduce the amount water carryout over from previous flotation reagents as this could affect the second flotation process, tungsten and also create a more effective circumstance for high solids density. The thickener underflow at 55% solids goes to the second rougher and scavenger flotation tank, tungsten. From the second valuable separation and second thickener, the tungsten concentration would range from 7 to 8%. Its concentration will be increased to a marketable 65% by heating the particles at 90min for 90oc. This tungsten then goes the third and last rougher and scavenger flotation process.
The final concentrate tungsten is filtered and dried before heading to the storage drum. The final moisture content is 3% and the load out of tungsten is at 15.12 tons/day.
Chemical Process Overview
The tungsten material can be separated from the gangue material with the use of flotation technique. The concentrate can be formed when the tungsten is separated from the gangue. The gangue includes carbonate sedimentary rocks, calcium carbonate layers and molybdenum. For the flotation, organic acid mixture and oil such as pine oil are used in the extraction of tungsten. Process water and adjusting of pH are added and done before the pulp is transferred to the flotation tank. Process water is used to control the solid density at 35% making it suitable for the flotation and pH is controlled by adding lime and reagents.
The Final grade and net returns
A final concentrated grade of 65% tungsten will be produced and marketed. Tungsten will be recovered at an estimation of 81% with the average yield of 0.86%. The saleable tungsten is produced at 15.12 Tons/day. The profits for this project is high and the operation is expected to last at least 8 years. There is more areas potential for mining tungsten. Forecast shows the cost of production for tungsten will continue to increase from the current $370/mtu to $400-$500/mtu in near future. This will increase the net profit for the company.