Resizing of Irrigation Pumps Used for Heap Leaching in a Mine: Case of SOMAÏR

Abstract

The aim of this study is the analysis and resizing of irrigation pumps used in heap leaching at the Mines de l'Aır company. This company is located in the Arlit department in the Agadez region of Niger. This work essentially consisted of checking the current pumps, integrating the new parameters and choosing the right pumps, either by respecting the current standard or by proposing other types of more efficient pumps. The study revealed that for the 3rd stage pumping circuit, the Total Head (HMT) value of 33.58 m is lower than that of the pumps, which is 34.03 m. This pump sends the fluid to the desired heap height with a pressure of 0.5 bar, whereas the desired pressure for watering is around 2 bar. The result: a drop in uranium juice production. The pump does not exhibit cavitation, as the Net Positive Suction Head (NPSHD) is equal to 4.71 m, a value that far exceeds the NPSHr , which is equal to 1.44 m. Given that at 1485 rpm the pump is unable to deliver a pressure of 6 bar with the valve closed, we can say that the pump has lost its performance. By the 3rd stage, the HMT of the circuit is equal to that of the pump, so the pump will still be able to deliver the fluid to the piles, but at a very low pressure, and even if both pumps are switched on simultaneously, the flow rate will not exceed 150 m3 /h. This means that irrigation will be very poor, resulting in mediocre uranium juice production. With a pump efficiency of 61.98%, we can say that the pump is operating under optimum conditions and does not suffer from cavitation, as the NPSHD is well above the NPSHr . For the 4th stage circuit, the CPKN 100-404 pump driven at 1650 rpm gives a flow rate of 175 m3 /h and a head of 57.91 M.C.E. The MegaCPK 125-80-380 pump driven at 1750 rpm gives a flow rate of 190 m3 /h and a head of 60.28 M.C.E. The CPKN 150-440 pump, driven at 1450 rpm, operates at 230 m3 /h and 67.55 M.C.E. The MegaCPK 150-125-380 pump, driven at 1750 rpm, delivers 250 m3 /h and a head of 71.71 M.C.E.