According to initial studies and excavations on God-E-Kolvari mine and the reserve estimation of around one million ton oxide copper ore, our company decided to invest on this reserve and setting up Cupex plant.
The nominal capacity of this line is 400 tons per year, which currently produces with a lower efficiency and with a capacity of 360 tons per year.
The product of this factory is oxide copper powder with 80% grade. Therefore, the required raw materials for this line are oxidized copper ore and its method is based on dissolution and leaching. This method consists of three general steps as following:
⦁ Crushing line design:
Crushing department contains two lines as following:
This line contains equipment as following:
⦁ Grizzly chute QTY=1
⦁ Hopper QTY=1
⦁ Uniaxial vibrating Feeder QTY=1
⦁ Uniaxial screen QTY=1
⦁ Belt conveyor QTY=5
⦁ Hydro cone QTY=1
The capacity of this line is about 70 to 80 ton per hour and its layout is as following:
This line contains equipment as following:
Uniaxial vibrating Feeder QTY=1
Jaw crusher QTY=1
Belt conveyor QTY=2
The capacity of this line is about 80 to 100 ton per hour and its layout is as following:
The procedure of crushing line and how they work is that hoppers are fed by truck or loader with depot ore and then on the one hand in first line (as it is shown in the picture) the ore is sent to screen by vibrating feeder and after that the minerals are divided to three grades that the most part is fine soil and rest is stones with the size of around 50mm and bigger. The stones with the size of less than 50mm will be sent to the heap and the larger will be sent to the hydro cone to be crushed in smaller parts, after that these ores will be sent to the heap for leaching. Temporarily fine soils are stored. On the other hand in second line (as it is shown in the picture) the large size of ore which is separated by grizzly in the first line will be sent to this line to be crushed an reach the optimum size (up to 50mm) and then they will be sent to the heap for leaching.
⦁ Leaching (Liquidation)
In this step crushed ores are exposed to a dilute solution of sulfuric acid (at a certain PH) to release its elements (copper). The product of this step is pregnant liquid Solution (PLS) which is feed for the next level.
Heap leaching is designed on the basis of the recovery percentage of 60%. To supply this condition the PH of the solution should be between 1-1.5. If this number goes upper than 1.5, then the kinetics of liquidation reduce drastically. The PH above 2.5 will stop the liquidation. The acid which is supposed to add to the heap should be analyzed and it should have the purity of minimum 95%. The density of copper in the PLS is function of heap performance, that if the density of PLS reduces, the heap is getting into a trouble or it is the end of liquidation period. Recognizing one of these is based on calculations which show the amount of copper on the heap. In this case, the amount and the purity of ore on the heap is specified, also the amount and the purity of production is specified, too. Eventually, due to the density of copper in the PLS and the volume of working solution it is possible to calculate the performance of leaching.
The equipment which have been installed and used in this department is as follow:
⦁ Anti-acid pump for transferring the solution QTY=5
⦁ Vacuum tank QTY=3
⦁ Liquidation liners Sufficient amount
The items which is necessary to be checked on the heap is as follow:
⦁ To avoid channeling the solution between the ores, the liners should be moved between 10cm to 20cm and also descaling on a daily basis.
⦁ The flow of the solution on the heap should be continues otherwise heap, piping and pumps would get into trouble.
⦁ Factory Design
The extraction method from the inlet PLS is based on electrolyzing.
The list of equipment which is used in the factory is as following:
PLS storage tank QTY=3
Acid storage tank (50.000 liter) QTY=1
Electrolyzing cells QTY=360
Structure for cells QTY=1set
Anode and Cathode plates QTY=720
Filter Press (50*50) cm2 QTY=1
Anti-acid pump QTY=1
Electric Panel QTY=1set
The procedure and how it works is that the solution is sent from PLS storage tank to the electrolyzing cells. In the cells, the DC electricity power is supplied and transferred to the anode and cathode plates and there the electrolysis operation is performed. After that the copper concentrates will be removed from cathode plates and will be poured on the bottom of the cells and with opening the outlet gate for 5 seconds the produced powder will be transferred to the thickener.
The items which should be monitored are as following:
⦁ Current flow 320-380 AMP
⦁ Density of copper in the inlet PLS 6-8 gr/lit
Also the power which is produced by rectifiers is computable by the following formula:
V = I * R
In this formula the amount of voltage is fixed, so increasing the resistance will reduce the current flow and reducing the resistance will cause increasing the current flow. The factors which will cause increasing resistance and as a result reducing the electrolyze efficiency, are existence of other elements such as Fe in the PLS, reducing the temperature, increasing the PH, reducing the copper density of PLS, etc.
Totally the layout of the processing system is as following schematically:
Description of the equipment shown in the picture is as following:
No1 – Crushing department
No2 – Heap
No3 – Ponds
No4 – Pumps
No5 – PLS storage tanks
No6 – Acid storage tank
No7 – Electrolyzing cells
No8 – Rectifiers
No9 – Vacuum tanks
No10 – Filter press
No11 – thickeners
Also there is a weighbridge with the capacity of 60 tons in the site and another balance with the capacity of 300 kg for measuring the amount of production.
A water tank with the capacity of 27.000 liters exists for general purposes and washing the production (If necessary).
Also two diesel generators with the power of 600kw exist to supply the electricity power until the permanent high voltage posts (with the power of 1250kw) are supplied.
⦁ Laboratory Equipment
The laboratory contains equipment as following:
⦁ Spectrophotometer QTY=1
⦁ Atomic Absorption QTY=1
⦁ Mill QTY=1
⦁ Furnace QTY=1
⦁ Balance QTY=2
⦁ PH-meter QTY=1
⦁ General Equipment Sufficient amount
⦁ Raw Materials Sufficient amount
In the mentioned laboratory tests as following are performed:
⦁ Purity of the production
⦁ Humidity of the production
⦁ Measuring the PH
⦁ Measuring the copper density of the PLS
⦁ Measuring the purity of the using ore
⦁ Measuring the purity of the using acid
It should be noted that raw materials such as water and acid are added into the ponds, that acid is added into the first pond (upper side of the heap) and water is added into the second pond (bottom side of the heap).