Lithium ores often contain various impurities, and achieving purification in lithium ore beneficiation requires separating these impurities from lithium to improve the purification process. Common impurities include iron, sulfur, phosphorus, and feldspar. Here, we present a case study that provides insights into how to separate feldspar from lithium ore.
XinHai Mineral Dressing Design Institute, after conducting elemental analysis and beneficiation tests on the ore, designed a process flow of crushing → grinding → desliming → flotation → magnetic separation for this project.
The crushing process design follows the principle of more crushing and less grinding, employing a three-stage closed-circuit crushing process to achieve a final crushed particle size of below 15mm. Jaw crushers are used in the coarse and medium crushing stages, while a cone crusher is used for fine crushing, complemented by a circular vibrating screen for screening during the crushing stages.
The operational process is as follows:
(1) The feeder sends the lithium ore to the jaw crusher for the first-stage crushing. (2) The product after the first-stage crushing is transported by a conveyor to another jaw crusher for the second-stage crushing. (3) The product from the second-stage crushing is screened by a circular vibrating screen. (4) Oversized material from the screening returns to the second-stage crushing for further comminution, while undersized material is sent to the cone crusher for the third-stage crushing.
In the grinding stage, a single-stage grinding process is employed for improved grinding efficiency and better separation of feldspar from lithium ore. The equipment used in this stage includes a wet grid-type ball mill and a spiral classifier.
The operational process is as follows:
The material after crushing is pumped into the grid-type ball mill from the feeding hopper for grinding. The product from the mill's discharge end enters a spiral classifier for classification. Overflow from the classifier returns to the mill for further grinding, while the underflow proceeds to the next stage, desliming.
Desliming in lithium ore beneficiation utilizes a inclined plate concentrator to dewater the slurry. As the concentrated slurry slides down the inclined plate, it undergoes compression and dewatering due to gravity, resulting in the removal of fine particles.
Flotation is a critical step in separating feldspar from lithium ore. The process flow design consists of a roughing stage, a scavenging stage, and three cleaning stages. Equipment used in this stage includes flotation machines and agitation tanks.
The operational process is as follows:
(1) The overflow slurry from the concentrator is mixed with reagents in the agitation tank. (2) After stirring, the mixture is fed into the flotation machine to complete the roughing, scavenging, and three cleaning stages. SF flotation machines are used in the cleaning stages, with middlings returned sequentially. Ultimately, high-grade lithium concentrate is obtained. (3) The tailings from flotation enter the magnetic separation stage, where iron is removed through magnetic separation to obtain high-purity (relatively white) feldspar concentrate.
The magnetic separation stage is designed for the tailings from flotation to further purify the feldspar concentrate, resulting in higher purity feldspar. The equipment used in this stage includes magnetic separators and high-frequency fine screens.
The operational process is as follows:
(1) The tailings from flotation are sent to a high-frequency fine screen for slag separation. (2) The slag-separated tailings undergo 1-2 rounds of strong magnetic treatment to obtain high-purity feldspar powder.
Through these five stages, feldspar separation in lithium ore is achieved, yielding lithium concentrate and high-purity feldspar concentrate, with a feldspar content reaching up to 62%. This project achieved favorable production results. In actual production, a reasonable beneficiation process should be determined through beneficiation tests, avoiding direct application without considering variations in ore properties, which may lead to resource wastage and unsatisfactory results.
