Tantalum & Niobium Mineral Processing in The World

Tantalum-niobium ore beneficiation generally uses gravity separation. First, discard most of the gangue minerals to obtain low-grade mixed coarse concentrates. The mineral composition of the coarse concentrates entering the beneficiation operation is complex and generally contains a variety of useful minerals. It is difficult to sort. Usually, a variety of beneficiation methods such as gravity separation, flotation, electromagnetic separation, or a combined process of beneficiation and smelting can be used to separate a variety of useful minerals.

Foreign Tantalum And Niobium Mineral Processing

When processing ores with a high content of fine ores or primary mud, ore-washing operations are essential. The weathered pegmatite alluvial clay roughing plant at Greenbush Mine in Australia has two ore washing systems. After the raw ore is washed twice with a cylindrical screen with a diameter of 1.5m and an aperture of 10mm, the ore is selected under the screen, and the large pieces and The clay balls enter the autogenous mill and are ground about 4mm, and then screened with a cylindrical screen with a hole diameter of 10mm. The materials under the screen are selected, and the materials above the screen are discarded or returned to be ground again. The water consumption for ore washing is 5m³/t, and the processing capacity of the cylindrical screen reaches 350 TPH.

Foreign tantalum and niobium concentrators attach great importance to the use of high-efficiency grinding and classification equipment to reduce the mudification of tantalum and niobium minerals. The primary pegmatite roughing plant of Greenbush Mine has achieved good results by using a peripheral discharge rod mill and a vibrating screen closed circuit. The Burnic Lake tantalum mine in Canada has been continuously improved, and the current grinding process is very unique. The mine uses a Ф2.4m×3.6m Marcy type grid ball mill A-C horizontal vibrating screen (linear screen) closed circuit, the screening particle size is 2.5mm, and the Drake screen is used under the screen to classify the particles according to 0.2mm, -2.5+0.2mm. The final grade is separated by a spiral concentrator, and the tailings are dehydrated through a curved screen and then returned to be ground again. The ball mill has two products that form a cycle, that is, one mill is used to achieve two-stage closed-circuit grinding. After adjustment, the cyclic load rate of the grinding circuit is usually about 180%. A small cyclic load can easily cause over-crushing.

The rough separation of tantalum-niobium iron ore abroad is still mainly based on gravity separation and efficient gravity separation equipment is often used with a simple process. For example, the Greenbush mine directly uses a jig to roughly select -10mm raw ore. The gravity separation-flotation-gravity process formed in the Burnick Lake tantalum mine in Canada in the 1980s has been increasingly improved. This process is still based on gravity separation, and flotation is only used to process fine mud. The gravity separation equipment adopts a GEC spiral concentrator, 3-layer suspended Dest shaker, Holman slime shaker, and cross-flow belt concentrator. The former Soviet Union used flotation to separate tantalite, fine crystals, and topaz from gravity separation concentrates. The collector was hydroxamic acid and the adjuster was oxalic acid. Flotation was carried out in a hydrochloric acid medium (pH 2). When feeding the ore When containing 2.52% Ta2O5, the concentrate grade is 27% and the recovery rate is 90%.

The beneficiation method of pyrochlore ore mainly adopts the flotation method. To improve the quality of concentrate and reduce the consumption of chemicals, in recent years, the pyrochlore beneficiation process has strengthened desliming, iron removal, desulfurization, phosphorus, lead, barium, and other operations. Niobek pyrochlore ore -0.2mm selected raw ore uses a cyclone to remove -10μm sludge and separates it according to mud and sand. First, use a fatty acid collector to flotate apatite and carbonate minerals, then conduct magnetic separation to remove iron, then use an amine collector to flotate pyrochlore, and finally conduct pyrite flotation on the pyrochlore concentrate. and hydrochloric acid leaching to reduce sulfur, phosphorus, and carbonate mineral content. When the raw ore contains 0.6%~0.7% Nb2O5, the final concentrate grade is 58%~62% and the recovery rate is 60%~65%.

China Tantalum Niobium Mineral Processing

1. Rough Separation of Tantalum And Niobium Ore

The raw ore grade of China tantalum-niobium ore is generally very low, and its mineral nature is brittle and dense. In order to ensure the grinding particle size and avoid over-crushing, the stage grinding and separation process is generally adopted.

A tantalum-niobium concentrator in Jiangxi uses a lateral arc screen instead of a linear vibrating screen for screening. The on-site exploration test results show that the fine clamping on the screen can be reduced by 14.70%, the coarse clamping under the screen can be reduced by 4.3%, and the screening efficiency can be increased by 17.72%. The successful test of this equipment provides a new way for on-site grinding and screening transformation. There is a large granitic pegmatite deposit in Nanping, Fujian. In 1998, a mineral processing test study was conducted on the ore to provide a design basis for the construction of the plant. Based on the particle size distribution characteristics of tantalum, niobium, and cassiterite minerals, it was proposed to adopt stage grinding and stage separation. The first section uses a rod mill and forms a closed circuit with the screen to reduce over-crushing. The second stage of grinding uses a ball mill and forms a closed circuit with a high-frequency vibrating fine screen. In addition to strictly controlling the particle size, it can also increase processing capacity and improve grinding efficiency. The ore roughing adopts a single gravity separation process. Gravity separation equipment includes a GL spiral concentrator, spiral chute and shaker. The raw ore selected from this mine contains (TaNb)2O5 0.0499% and Sn 0.0598%. The crude concentrate yield obtained after rough separation is 0.248%, containing (TaNb)2O5 14.94% (including Ta2O5 10.79%). The recovery rate of the raw ore is 0.248%. 74.30% (Ta2O5 recovery rate is 74.96%); contains Sn 15.71%, and the recovery rate of raw ore is 65.11%.

2. Tantalum-niobium Ore Featured Separation

The coarse concentrate obtained by the rough separation process is generally a mixed coarse concentrate, which needs to be further refined to separate a variety of useful minerals. The mineral composition of coarse concentrates is different, and the separation methods used are also different. Generally, multiple methods are used in combination. 
For example, Fujian Nanping tantalum and niobium selection use a combination of magnetic-gravity-floatation. First, use a 6% hydrochloric acid solution to clean the mineral surface, then use weak magnetic separation to remove strong magnetic minerals and iron filings. Dry and screen the materials into +0.2, +0.1, and -0.1mm. The tantalum and niobium concentrates are obtained through one rough separation and one sweep with a dry strong magnetic separator. The non-magnetic part of the dry strong magnetic separation is recovered by gravity separation and tailed. The selected concentrate is floated to remove sulfide ore to obtain tin concentrate.
Concentration results: The yield of tantalum niobium concentrate is 0.0764%, containing (TaNb)2O5 45.64% (Ta2O5 32.57%), the recovery rate of raw ore is 69.92% (Ta2O5 recovery rate 69.071%), the recovery rate of the concentrating operation is 94.11%; the tin concentrate production The rate is 0.0581%, containing Sn60.25%, the recovery rate of raw ore is 58.49%, and the recovery rate of beneficiation operation is 89.84%.

3. Flotation of Fine-grainedTantalum-niobium Ore

An ore body in Jiangxi is a large tantalum-niobium-tungsten granite ore body. The main useful minerals in the ore are wolframite, scheelite, tantalum-niobium iron ore, and fine crystals. The useful minerals are embedded in very fine particles, and most of them are at 40~74μm, therefore using the conventional gravity separation method, the mineral processing recovery rate is low, and the tantalum recovery rate is only 25%~33%. After using the heavy-floatation combined process to recover tantalum, niobium, and associated tungsten minerals, when flotation feeds WO3(0.088%) and Ta2O5 (0.0145%), the flotation concentrate yield is 0.7%, and the concentrate contains 10.84% WO3 and 1. 8% Ta2O5, the recovery rates of tungsten and tantalum are 85% and 87% respectively, and the concentrate enrichment ratio is more than 100 times. Then it is re-selected and enriched, and tantalum and tungsten are separated by hydrometallurgy. The tantalum beneficiation and smelting recovery rate reaches 44%.

The ore properties of a certain mine in Baotou are very complex, especially niobium minerals, which are famous for being poor, fine miscellaneous, and difficult to separate. Although the current mineral processing technology has made great progress compared with the past, the recovery rate of rare earth mineral processing is still low. The mineral processing of niobium recycling is still in the research stage. The flotation method is used to enrich niobium minerals from rare earth flotation tailings. Pb(NO3)2 is used as the activator, D-1 is the inhibitor of calcium minerals, and the combined collector mainly uses hydroxamic acid. At pH 6 Niobium flotation is carried out in the medium. After the desulfurization of the niobium coarse concentrate enriched by flotation, the weak magnetic—shaking table process is used to concentrate to obtain niobium-rich iron ore concentrate and iron ore concentrate. The rich ferroniobium concentrate 1 contains 1.66% Nb2O5, concentrate 2 contains 0.59% Nb2O5, and the total niobium recovery rate is 35.58%. After the rare earth flotation tailings are concentrated and deslimed, oxidized paraffin soap, water glass anti-floating fluorite, and residual rare earth minerals are added. After the products in the tank are concentrated, ammonium fluorosilicate and oxidized paraffin soap are added to flotate the iron minerals to obtain Iron concentrate, select iron tailings and add sulfuric acid, carboxymethyl cellulose, salicylic hydroxamic acid, C5-9 hydroxamic acid and oxalic acid. After one rough selection and three times fine selection, niobium containing 1.67% Nb2O5  and a recovery rate of 40.14% is obtained. The flotation concentrate is then separated from iron and niobium by strong magnetism to obtain niobium concentrate as a non-magnetic product and niobium sub-concentrate as a magnetic product. In addition, the magnetic-flotation process can also obtain rare earth foam products and iron ore concentrates.