How to Prepare High-purity Homogeneous Acicular Violet Tungsten Oxide

Tungsten carbide powder is the main raw material for the production of cemented carbide, and ultra-fine tungsten carbide powder is also the main raw material for ultra-fine grained cemented carbide. 

Therefore, from the perspective of perfecting the industrial chain, the preparation of high-purity homogeneous ultra-fine tungsten carbide powder has very Important scientific value. Compared with ordinary tungsten carbide powder, high-purity homogeneous ultra-fine tungsten carbide powder puts forward more stringent requirements on raw tungsten oxide powder. At present, high-purity homogeneous acicular violet tungsten oxide is the most suitable for the raw material of ultra-fine tungsten carbide powder. How to prepare high-purity homogeneous acicular purple tungsten oxide powder? The process is listed below:

(1) Preparation of raw materials: the ammonium tungstate feed liquid is added to the circulating pipe, mixed with the circulating mother liquor in the circulating pipe, and is pumped to the heat exchanger by the circulating pump. The heated solution is transported in the crystallizer body to evaporate and reach saturation, and then through the central tube to reach the central guard plate, the central guard plate bears and disperses the impact force of the circulating liquid from the central pipe, the newly crystallized crystals are deposited on the bottom of the crystallizer body by gravity, and the circulating mother liquor goes up to the next cycle. To obtain uniform high-purity single crystal ammonium paratungstate crystals.

(2) Raw material pretreatment: particle size classification of high-purity single-crystal ammonium paratungstate through screening equipment to obtain fine-particle high-purity single-crystal ammonium paratungstate with a certain particle size composition.

(3) Ammonia gas: The fine particles of high-purity single crystal ammonium paratungstate in S2 is placed in a φ400 rotary kiln, ammonia gas is introduced, the rotary kiln is heated, the ammonia gas is cracked into hydrogen and nitrogen, and the hydrogen atmosphere is used to slightly reduce the raw materials. High-purity homogeneous needle-like purple tungsten powder is obtained.

Note: The model of the screening equipment in the second step is DY-1200-2S. The vibrator of the screening equipment adopts a simple vibrator. The temperature of the rotary furnace mentioned in the third step should be controlled at 500-800 degrees Celsius. In the third step, the flow rate of ammonia gas into the rotary furnace is controlled at 0.5-2m3/h. In the third step, the feed rate in the rotary furnace is 0.01-0.2 tons/h.

Compared with the prior art, the preparation method has 5 advantages:

(1)The high-purity single crystal ammonium paratungstate prepared by a specific crystallization process is used as the raw material, and the total amount of impurity elements is controlled below 60ppm, which is beneficial to the source control of impurity elements.

(2)By controlling the particle size composition of the high-purity single crystal ammonium paratungstate raw material, it is beneficial to control the morphology and uniformity of the subsequent purple tungsten, ultrafine tungsten powder, and ultrafine tungsten carbide powder.

(3) Ammonia replaces hydrogen reduction during the reaction process, which is conducive to controlling the micro-reduction atmosphere and eliminates the safety hazards caused by hydrogen.

(4) The purple tungsten oxide powder prepared by this method has high purity, single phase, large specific surface area, good fluidity, impurity element K and Na content ≤ 1ppm, and excellent performance.

(5) The process of preparing high-purity homogeneous acicular purple tungsten powder by using rotary furnace high-temperature micro-reduction of high-purity single crystal ammonium paratungstate has the characteristics of short process, low cost, simple and controllable process, and simple operation.

• < Prev
• Next >