How To Process Nickel Laterite By Acid Leaching

There are two types of laterite nickel beneficiation: pyro-smelting process and wet process.

The pyro-smelting process for nickel recovery has been used earlier and the technology is relatively mature, but it also has the disadvantages of being limited by power supply, high investment and high pollution.

With the development of science and technology, the wet process has become more and more mature. The commonly used laterite nickel wet beneficiation process is the acid leaching process. 

For different types of laterite nickel, Laterite Nickel Acid Leaching Process can be divided into atmospheric pressure acid leaching process, pressure acid leaching process, atmospheric pressure + high pressure combined acid leaching process.

Laterite Nickel Atmospheric Pressure Acid Leaching Process

Atmospheric pressure acid leaching is suitable for treating laterite nickel ore with high magnesium content, and sulfuric acid and hydrochloric acid are generally used as leaching agents.

After grinding the laterite nickel ore to make a certain concentration of ore slurry, add a certain concentration of acid, and control the temperature to leaching elements such as nickel, cobalt, iron, magnesium and aluminum in the ore.

Then use alkali to neutralize the ore pulp to remove impurities such as magnesium, iron, and aluminum. After liquid-solid separation and washing, the obtained liquid is subjected to precipitation treatment to obtain nickel oxyhydroxide cobalt. The remaining liquid is re-neutralized to remove calcium, and magnesium is returned to production and a part of discharge.

The iron in the leaching solution of laterite nickel ore is converted into ferric phosphate, which is further processed into ferrous lithium phosphate.

Laterite Nickel Pressure Acid Leaching Process

The pressure acid leaching process is suitable for the treatment of laterite nickel ore with high limonite content and low magnesium content.

First, the laterite nickel ore is ground into a stable slurry, which is preheated and leached under a stable sulfuric acid concentration.

During leaching, elements such as nickel, cobalt, iron, and aluminum are dissolved together. After the slurry is separated and washed, impurities such as iron and aluminum enter the slag, while nickel and cobalt remain in the solution.

According to the requirements of the product scheme, different processes can be used to produce high-quality nickel-cobalt hydroxide, nickel-cobalt sulfide or nickel-cobalt sulfate crystals.

Laterite Nickel Combined Acid Leaching Process

Atmospheric pressure + high pressure two-stage acid leaching treatment of laterite nickel ore can be used for ores with different magnesium contents in one ore body.

The acid leaching process will produce excess acid after treatment, and neutralization treatment is required in the purification process of the leachate in the later stage, which will affect the subsequent impurity removal operations to varying degrees.

Therefore, Xinhai has studied the two-stage leaching process based on the two processes of normal pressure acid leaching and high pressure acid leaching.

The main purpose of using the combined process of atmospheric leaching + high-pressure acid leaching to treat laterite nickel ore is to neutralize the excess acid in the leaching solution, thereby removing part of the ferric iron.

Adding low-magnesium type minerals to the acid leaching solution of high-magnesium type laterite nickel ore at atmospheric pressure to carry out two-stage high-pressure acid leaching can neutralize free acid.

In actual production, it is necessary to select an appropriate process according to the mineral composition and ore properties of laterite nickel, which can be determined by professional processing tests.