The main useful minerals in a certain spodumene mine are spodumene, tantalum niobium iron ore, and cassiterite, while the main gangue minerals are quartz and feldspar. In order to comprehensively recover tantalum niobium iron ore and cassiterite, a combined process of gravity separation magnetic washing flotation is adopted in the beneficiation process to obtain ideal beneficiation indicators.
The ore structure is mainly coarse grained, with fine-grained and textural structures, as well as peritectic structures. The structure is blocky and disseminated.
The ore belongs to pegmatite deposit, the main useful minerals are spodumene, tantalum niobium iron ore and cassiterite, and the main gangue minerals are quartz and feldspar.
1.1. Spodumene: It is the main lithium containing mineral. Spodumene is closely intertwined with quartz and feldspar in the ore, and is also commonly found in quartz or feldspar particles, which contain fine needle shaped spodumene particles. The maximum particle size of spodumene is 20 × 50mm, minimum 0.05 × 0.1mm, with a general particle size of 1 × 3mm。
1.2. Tantalum niobium iron ore: The types of tantalum niobium minerals in this ore have been identified, mainly including tantalum niobium iron ore and manganese tantalum ore. The color of tantalum niobium iron ore is black or brownish black. Manganese tantalum ore is brownish red in color. Tantalum niobium sand is often embedded with quartz feldspar in ores, with a maximum particle size of about 1mm, a minimum of 0.01mm, and generally 0.05-0.5mm. The measured specific gravity of tantalum niobium iron ore is 5.86.
1.3. Cassiterite: mostly brown and light brown, with a maximum particle size of 1mm, a minimum of 0.05mm, and generally 0.1-0.6mm.
The comprehensive recovery of three minerals mainly involves the following three beneficiation processes:
2.1. Magnetic separation
Tantalum niobium iron ore, manganese tantalum ore, and cassiterite have a higher specific gravity than spodumene and gangue minerals, and can be separated by gravity separation. The main minerals in the gravity concentrate are magnetite, tantalite, manganese tantalite and cassiterite. By utilizing the different specific magnetization coefficients of each mineral, a separation process of weak magnetic separation followed by strong magnetic separation is adopted for separation.
2.2. Flotation
The minerals after magnetic separation should be roughened using flotation technology, and attention should be paid to the control of grinding fineness, feed concentration, and feed volume during roughening:
(1) Grinding fineness
From the results of tailings screening analysis, it can be seen that the Ta2O5 metal content in tailings below -200 mesh accounts for 55.09% of the Ta2O5 metal content in coarse tailings. In order to reduce the loss of fine-grained tantalum niobium ore, it is necessary to carefully select the grinding particle size. In order to avoid excessive grinding and mud formation, it is necessary to choose a coarser grinding particle size when determining the grinding particle size.
(2) Feed concentration
During the experiment, as the feed concentration increases, the concentrate yield gradually increases. The concentrate recovery rate and grade first increase and then gradually decrease with the increase of concentration. In this experiment, when the feed concentration is 30%, the sorting index is better.
(3) Ore feeding capacity
When the ore feed rate increases from 700kg/unit · h to 1100kg/unit · h, the concentrate grade increases, but the recovery rate decreases significantly. The appropriate amount of ore to be fed should be 800kg/unit · h.
The coarse concentrate is subject to two-stage cleaning (gravity separation) with a shaker. There are 69.25~72.86% cassiterite and 6.52%~12.19% magnetite in the concentrate and middling. Magnetite is a strong magnetic mineral, while tantalum niobium iron ore and cassiterite are weak magnetic minerals. Therefore, magnetite can be separated by weak magnetic separation.
Tantalum niobium ore and cassiterite have a significant difference in specific magnetization, so they can be separated by strong magnetic separation. The strong magnetic concentrate is qualified tantalum niobium concentrate, and the strong magnetic tailings are cassiterite concentrate.
After selection, the grade of Ta2O5 in tantalum niobium ore has reached over 19%, and the grade of cassiterite concentrate has exceeded 65.58%.
