Introduction to Niobium Tantalum Beneficiation

Tantalite niobate is mainly composed of tantalum, niobium tin, tungsten, lithium, beryllium and other polymetallic ores. It has the characteristics of low grade of raw ore, complex mineral composition, high mineral density and brittle property. After years of experience, Fodamon engineers have concluded that the mineral processing methods mainly include gravity separation, magnetic separation, electrical separation, floating gravity separation, flotation and chemical treatment. The beneficiation process is generally divided into two parts: roughing and cleaning.

a. Tantalite niobate roughing

The gravity separation process is mainly used for the roughing of tantalite niobate, but gravity separation flotation gravity separation is also used; Gravity separation flotation or gravity separation magnetic separation gravity separation.

(1) Reselection process

The primary tantalum niobium ore is mainly subject to stage grinding and multi-stage gravity separation. Separation equipment is usually added in the grinding circuit to recover monomer minerals in advance. Tantalum niobium placer generally does not need to be broken and ground due to good dissociation of mineral monomer. Screening shall be carried out before being selected to remove block stones and pebbles, and then rough separation shall be carried out. Coarse grained tantalum niobium iron ore is roughened by jigging machine or spiral concentrator (including rotary spiral chute), and the roughing concentrate is cleaned by shaking table; Fine grained tantalum niobium iron ore is roughened by spiral chute or shaking table, and the roughing concentrate is cleaned by shaking table; The tantalum niobium slime is roughed by centrifugal concentrator or multi-layer turning bed, and the roughing concentrate is cleaned by belt chute or trough flow belt chute combined with slime shaker. This process is characterized by less investment, fast start-up, low cost and less environmental pollution. But the efficiency of slime separation is low.

Gravity separation – flotation – gravity separation or gravity separation – flotation process: gravity separation is adopted for coarse and fine-grained materials and flotation is adopted for slime. Before flotation, small-diameter cyclone or centrifugal concentrator is generally used for desliming, and then alkylsulfonated succinate is used as collector, sodium silicate and oxalic acid are used as adjusters for flotation under the condition of pH 2-3. The flotation concentrate is cleaned by Holman slime shaker cross flow belt chute; Alternatively, styrene phosphonic acid is used as collector, sodium fluosilicate and lead nitrate are used as adjusters, and flotation is carried out at ph6. The flotation concentrate is cleaned by vibrating belt chute or cross flow belt chute, or hydroxamic acid and transformer oil (2:1) are used as collector, sodium hydroxide and sodium silicate are used as adjusters, and flotation is carried out at ph8-8.5. Hydroxamic acid and transformer oil are added to the flotation concentrate, and oxalic acid is used as inhibitor, Under the condition of pH 2.5-3. Tantalum iron ore or niobium iron ore concentrate can be obtained by the above methods. This process is characterized by high separation index, but the content of tantalum and niobium in the removed fine mud is close to the grade of raw ore, large reagent consumption and high production cost.

(2) Gravity separation magnetic separation gravity separation process

Gravity separation is adopted for coarse-grained materials. The combination of magnetic separation and gravity separation is adopted for fine particle and slime. This process is characterized by high separation efficiency for fine-grained tantalum iron ore and niobium iron ore, but the tantalum niobium minerals in the ore must have weak magnetism.

b. Cleaning of tantalite niobate coarse concentrate

Tantalite niobate coarse concentrate is generally complex in composition and difficult to separate. It is often necessary to adopt one or two or more methods of magnetic separation, gravity separation, floating gravity separation, flotation, electrical separation, chemical treatment and other methods. In particular, the separation of tantalite and niobate from some difficult minerals requires a combination of multiple separation methods. For example, tantalite niobate is separated from garnet and tourmaline by magnetic separation, electrical separation or flotation.

(1) Magnetic separation

Their specific magnetization coefficient: tantalite is 2.4 × 10-5 cm3 / g, niobium ore is 2.5 × 10-5 cm3 / g, 5.8 × 10-5cm3 / g, garnet and tourmaline change with their iron content. When the Fe2O3 content of garnet increases from 7% to 25%, its specific magnetization coefficient increases from 11 × 10-6 cm3 / g, increased to 124 × 10-6 cm3 / g (11 times increase). When the Fe2O3 content of tourmaline increases from 0.3% to 13.8%, its specific magnetic coefficient increases from 1.1 × 10-6 cm3 / g, increased to 30 × 10-6 cm3 / g (30 fold increase). In order to improve the separation selectivity of minerals in the magnetic field, acid (solid: liquid = 1:5) is generally used for a short time (5-15 minutes) to remove the iron on the surface of minerals, and then garnet and tourmaline are separated in the magnetic field of different strength to obtain tantalum niobium concentrate.

(2) Electric separation

The materials shall be screened and graded in narrow grades, and then heated separately for electric separation in a composite electric field: the particles larger than 0.2 mm are generally selected with low voltage (20-35 kV), large polar distance (80-100 mm), slow speed (low centrifugal force) (the number of rotations of the roller or drum is 33-38 RPM) Generally, high voltage (35-45 kV), small polar distance (50-80 mm) and high rotational speed (high centrifugal force) are used for 0.2 ~ + 0.08 mm particle size fraction (the rotation speed of the roller is 70-118 RPM). Tantalite niobate can be separated from garnet.

(3) Flotation separation

Niobate and garnet can be separated by using sodium cetylsulfonate as collector and fluorine compound as regulator.

Separation of tantalum niobate from monazite

Electric separation is usually used for coarse grain size; For the fine particle (- 0.075mm), oleic acid or rice bran oil is used as a collector, sodium carbonate (Na2CO3) is used as a regulator, sodium silicate (Na2SiO3) and sodium sulfide (Na2S) are used as inhibitors (Na2SiO3 ∶ Na2S = 3:1). Monazite can be floated under the condition of PH9 to separate iron tantalite (niobate) from monazite.

(4) Separation of fine crystal and cassiterite

Electrostatic separation (voltage: 16 kV) is usually adopted for coarse particle grade; The fine particle is treated with 2% hydrochloric acid for 15 minutes, then sodium alkyl sulfate (600g / T) is used as a collector, and sodium fluorosilicate (Na2SiF6) is used as an inhibitor to float cassiterite under the condition of pH 2-2.3 to separate the fine crystal from cassiterite.

(5) Separation of tantalum niobate and magnetic CASSITERITE

The coarse particle is generally separated by wind shaking table; In the fine-grained grade, Guangzhou Nonferrous Metals Research Institute of China has developed a new magnetic separation process of oxidation roasting (800-900 ℃), which can well separate tantalum niobate, tantalum rutile and cassiterite.

(6) Separation of tantalum niobate and wolframite

Hydrometallurgy is usually adopted. First, grind the material to – 0.04 mm, add sodium carbonate (Na2CO3) for roasting (800 ℃), or boil it with concentrated alkali under normal pressure, and then decompose the filtered residue with HCl (5%) to obtain artificial tantalum niobium concentrate. The filtrate is sodium tungstate solution, and the tungsten oxide (WO3) product can be obtained by adjusting the acid (pH 2-2.5), extracting, neutralizing and crystallizing.

(7) Separation of niobate and zircon

Magnetic separation or flotation can be used. Sodium oleate can be used as collector in flotation, lead chloride, water vitrification or lead chloride and oxalic acid can be used as adjusters to separate niobate from zircon.

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