Tantalite and columbite whether natural form, or from the enrichment of tin slag, in particular temperature HF acid decomposition, associated elements and tantalum niobium dissolved, its form is H2NbF7 and H2TaF7, filtered in removing impurity (alkaline fluorides and rare element), the liquid phase in a continuous mixing tank with HF acid or mixed with organic phase such as MZBK extraction column, tantalum niobium in organic phase, and the impurity elements such as Fe, Mn and Ti in water phase and the residual liquid.
Organic phase Nb2O5 + Ta2O5 content is 150 ~ 200 g/l, organic phase usually after 6 ~ 15 n, and then use H2O or selective extraction - H2SO4 solution or backwashing niobium, aqueous phase containing fluorine niobate and residual HF acid, the fluorine tantalum acid in organic phase. Niobium containing trace MIBK and a small amount of tantalum extracted together.
Organic phase moves into the next Ta/Nb extraction procedure. Nb (OH) 5 is used to precipitate ammonia or liquid ammonia in niobium liquid. In organic phase, tantalum is extracted or washed by steam, water or dilute ammonia. Ta (OH) 5 is precipitated by ammonia, or potassium salt is added to the tantalum liquid to form K2TaF7.
Oxide precipitation can batch or continuous production, hydroxide by filtration, drying above 1100 ℃ calcination, different applications need different particle size distribution, there are different precipitation, drying and calcination conditions. Due to different quality requirements, direct or indirect roasting is carried out in the heating chamber or converter, and the furnace composition has a great influence on the oxide purity. For example, nickel chromium ferroalloy furnace into Ni and Cr impurities, the reasonable process control tantalum niobium products have high qualified rate (> 95%) and high purity (> 99.9%), the progress in the following way:
1. Improve process control conditions.
2. Accurately control and monitor process parameters such as content, acidity and flow.
3. Improve equipment use such as flow control equipment, special material equipment such as reinforced plastic or special ceramic lining drying and roasting equipment.
4. Use of precision analytical instruments, such as GDMS.
