Powder metallurgy tantalum powder and/or niobium powder and preparing method thereof

Abstract

The invention provides a preparing method of powder metallurgy tantalum powder and / or niobium powder. The method comprises the steps that (1) heat treatment sintering is conducted, wherein heat treatment sintering is conducted on raw tantalum powder and / or the niobium powder and after sintering is accomplished, cooling is conducted and then passivation is conducted so that a sintered block can be obtained; (2) hydrogenation and powder preparation are conducted, wherein the sintered block obtained through heat treatment is hydrogenated and powder is prepared so that the hydrogenated tantalum powder and / or the hydrogenated niobium powder can be obtained; (3) dehydrogenation and oxygen reduction are conducted, wherein reducibility metal is added to the hydrogenated tantalum powder and / or the niobium powder so that dehydrogenating and deoxygenating heat treatment can be conducted, and therefore a mixture of reducibility metallic oxide, residue reducibility metal, dehydrogenated and deoxidized tantalum powder and / or the niobium powder can be obtained; (4) acid pickling and impurity removal are conducted, wherein acid pickling and drying are conducted on a mixture obtained through dehydrogenation and oxygen reduction so that the tantalum powder and / or the niobium powder suitable for powder metallurgy can be obtained. The method is suitable for recycling and treating the waste tantalum powder and / or the niobium powder generated in the process of production of the high-specific-volume tantalum powder and / or the niobium powder for a capacitor so that the tantalum powder and / or the niobium powder suitable for powder metallurgy can be prepared, investment of needed devices is small, the adaptive capacity to raw materials is strong, the technological process is short, and the safety coefficient of the treatment process is high.

Description

technical field [0001] The invention relates to the field of rare metal smelting, and specifically relates to tantalum powder and / or niobium powder and a preparation method thereof. Background technique [0002] Tantalum and niobium are rare elements that behave very similarly. Tantalum and niobium oxide films are widely used in the fabrication of tantalum and / or niobium electrolytic capacitors due to their very high dielectric constants. In addition, because tantalum and / or niobium have a high melting point and low vapor pressure, they are also used in aerospace, national defense, and heating components, boats, and insulation materials in high-temperature vacuum furnaces. In addition, tantalum and / or niobium have excellent corrosion resistance to liquid metals and strong acids except hydrofluoric acid, and have good thermal conductivity and chemical stability, and are also used as anti-corrosion materials in the fields of chemical industry and metallurgy. In addition, due...

AI Technical Summary

Problems solved by technology

However, there are the following problems when recycling the waste tantalum and / or niobium powder produced in the production process of tantalum and / or niobium powder for capacitors by this method: 1) The above recycling method first needs to dissolve the waste tantalum and / or niobium powder with acid , this process produces a large amount of hydrogen, which is very prone to hydrogen deflagration accidents, so the production risk is extremely high; 2) The recycling rate of tantalum resources is relatively low; 3) The process is long and the production cost is relatively high; Environmental pollution is relatively serious

However, when the specific surface area of ​​the raw material tantalum and / or niobium powder is greater than 1.0m 2 / g, the bulk density of the powder will be very small (possibly less than 1.0 g / cm 3 ) and relatively high oxygen content (possibly higher than 6,000ppm)

When such tantalum and / or niobium powder is pressed into a billet, the following problems are prone to occur: the tantalum and / or niobium powder adheres to the inner wall of the mold, resulting in difficulty in releasing the film, so the work efficiency is reduced and even the billet cannot be pressed; and the method The pressing equipment used is complicated, so the equipment investment is relatively large

However, as the specific volume of tantalum and / or niobium powder used in capacitors is getting higher and higher, the specific surface area and activity of waste tantalum and / or niobium powder to be recycled are getting higher and higher. Or the specific surface area of ​​niobium powder is greater than 1.8m 2 / g or more, the strength of the sintered agglomerate after high temperature and high vacuum heat treatment is too high, which makes it difficult to break the sintered agglomerate, and it is easy to rub and catch fire when it is broken, causing a fire.

On the other hand, if the heat treatment temperature is lowered, the strength of the sintered block is reduced, but the activity of the tantalum powder is not effectively reduced; therefore, the passivation time after heat treatment is particularly long, which greatly reduces the production efficiency of the equipment, and in the subsequent treatment, the tantalum powder Tantalum powder is prone to spontaneous combustion and fire accidents; even if it does not catch fire, the treated tantalum powder still has a small bulk density

In addition, when a low heat treatment temperature is used, the specific surface area of ​​tantalum powder is still relatively large and the activity is relatively strong. During the process of handling, transportation, storage and use, tantalum powder is in contact with the air medium and reacts with oxygen, nitrogen and moisture in the air. Therefore, impurities such as oxygen, nitrogen, and hydrogen in tantalum powder are still very high, which cannot meet the requirements of tantalum and / or niobium powder for powder metallurgy

[0009] To sum up, the prior art of recovering and processing waste tantalum and / or niobium powder produced during the production of high specific volume tantalum and / or niobium powder for capacitors has the following disadvantages: (1) The equipment structure is complicated and the equipment investment is large ; (2) Low work efficiency; (3) Long process route and low recovery rate of tantalum powder, resulting in relatively high processing costs; The specific surface area and activity of waste tantalum and / or niobium powder are getting higher and higher, and the existing technology can no longer effectively treat it

The waste tantalum and / or niobium powder produced during the production of high specific volume tantalum and / or niobium powder for some capacitors is treated according to the existing process, not only can not obtain qualified tantalum and / or niobium powder for powder metallurgy, it may be due to / or niobium powder spontaneous combustion, a deflagration accident

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