Ammonia leaching treatment of laterite ore

High magnesium oxide laterite Ni Jialuo Treatment using Nickel in Cuba for a long time. Typical minerals suitable for treatment with this ammonia-alkali leaching method are 1.4% Ni, 8% MgO, 14% SiO2.

Ammonia leaching method is based on nickel laterite generally combined with the iron salt to iron status, by reduction roasting iron, nickel metal into nickel or a nickel-iron alloy, to dissolve in the ammoniacal solution. At present, the production scale of the Nile Plant in Cuba is 1780 kt (average nickel content 1.3%, cobalt 0.07%), sintered nickel oxide 16170t (Ni90%), total nickel yield 70.4%, cobalt leaching rate 18%-20 %, ammonia consumption 410kg / t nickel, carbon dioxide consumption is 551kg / t nickel.

The Nicaro nickel plant in Cuba has treated the high-magnesia nickel-containing laterite ore by reduction roasting-atmospheric ammonia leaching for half a century. The process is shown in Figure 1. The advantages of this process are as follows:

(1) The ammonium carbonate solution can selectively dissolve nickel, copper and cobalt in the calcine to form a stable complex, and can be successfully separated and recovered. The impurities such as iron, zinc and magnesium are mostly hydrolyzed and removed in the production process because of their low solubility.

(2) The ammonium carbonate solvent is easy to recycle and is returned for use.

(3) The material is weak in corrosion, and most of the equipment can be made of carbon steel.

(4) Using atmospheric pressure leaching, the equipment has a simple structure.

Figure 1 Cuba Nigaro smelter production process

The disadvantages of this process are as follows:

(1) High energy consumption. The total energy consumption of nickel produced from nickel sulfide ore is 22 kWh/kg nickel, while the total energy consumption of nickel oxide ore is 1 to 3 times larger than that of sulfide ore.

(2) The liquid-solid separation of leaching and washing operations generally adopts a thickener. The material stays in the system for a long time (about 72h), the equipment volume is large, and the plant area is large.