Application background and overview of nickel carbonate
Nickel carbonate mainly includes nickel orthocarbonate, basic nickel carbonate and acid nickel carbonate. Nickel carbon methoxypyridine also has anhydrous, trihydrate and hexahydrate. Basic nickel carbonate has two forms: 2NiCO3·3Ni(OH)2·4H2O and NiCO3 · 2Ni(OH)2·4H2O. Anhydrous nickel carbonate is a light green orthorhombic crystal. Heated to ℃, it decomposes into carbon dioxide and nickel oxide. Almost insoluble in water (0.0093 at 25°C), soluble in water containing carbon dioxide. Easily soluble in acid.
Hexahydrate [NiCO3·6H2O). Most of the products on the market are hexahydrate. Light green crystal. It becomes anhydrous after being heated and dehydrated. Dissolved in ammonium carbonate aqueous solution, it becomes a blue-green solution. After concentration, it can generate a double salt (NH4)HCO3·NiCO3·4H 2O. With aqueous solutions of sodium carbonate and potassium carbonate, green double salts can be produced. Both basic nickel carbonates are cubic green crystals. Acid nickel carbonate [Ni3H2(CO3)4] is hardly soluble in water and soluble in water. In carbon dioxide saturated aqueous solution, but after releasing carbon dioxide, it becomes nickel carbonate (NiCO3) and precipitates.
Application symptoms of nickel carbonate
Nickel carbonate can be used as a pigment for glass and porcelain; a raw material for other nickel compounds; and a catalyst. Examples of its application are as follows:
Applications of nickel carbonate 1. Prepare nickel sulfamate using nickel carbonate and solid sulfamate.
In this method, solid sulfamic acid is directly added to the slurried nickel carbonate to undergo an acid-base neutralization reaction to prepare a high-concentration nickel sulfamate solution, and then the nickel sulfamate solution is evaporated, Crystallize, centrifuge and dry to obtain nickel sulfamate product. The method of the present invention prepares a single raw material and has simple procedures without adding catalysts and other substances. It not only avoids the occurrence of side reactions caused by the addition of initiators, improves the purity of the nickel sulfamate product, but also obtains a high-concentration nickel sulfamate solution. The evaporation time is shortened, the production cost is reduced, and the yield is improved.
Applications of nickel carbonate 2. Nickel carbonate is used to improve the properties of sintered manganese-copper damping alloy.
The highly active nickel produced by thermal decomposition and hydrogen reduction of nickel carbonate is used to promote sintering. The released CO2 and H2O gases prevent the formation of a dense sealing layer on the surface of the sintered body, improve the uniformity of the sintered body, and allow sintering in a hydrogen atmosphere. A large-sized manganese-copper sintered body is obtained, which is pyrolyzed, reduced and sintered under the action of hydrogen. The specific steps are: nickel carbonate decomposition: 300-450°C holding time for 1-4 hours; nickel oxide reduction: ~550°C holding time for 1-4 hours; sintering: 850-950°C holding time for 1-4 hours; temperature rise rate 5-10°C /minute.
This method can sinter manganese-copper damping alloys with an alloy diameter of 100mm, a length of 220mm, a density of 5.18~5.73g/cm3, a hardness of 49~95HRF, and a bending strength of 126~278MPa. The main functions of using nickel carbonate instead of nickel powder as the donor of nickel element are:
① The fine nickel element produced by the thermal decomposition of nickel carbonate has a low melting point and can fuse elemental manganese powder at a lower temperature, thereby reducing the thermal resistance interface and improving the thermal conductivity and temperature uniformity of the sintered billet, thereby improving Uniformity of manganese-copper sintered alloy;
② In the temperature range where nickel carbonate decomposes, the surface of the compact has not been sintered and densified. Therefore, the water and carbon dioxide gas produced by the decomposition of nickel carbonate are continuously discharged from the surface of the compact, preventing the formation of a dense sealing layer on the surface of the compact, leaving the surface in a The porous state is conducive to the discharge of adsorbed water on the surface of the mixed powder during the low-temperature heating stage; during the high-temperature sintering stage, it is conducive to hydrogen entering the sintered body and reducing a small amount of oxidized metal elements;
③ Nickel carbonate is a fine powder and is not prone to plastic bonding, so it is conducive to even mixing of ingredients;
④The fine high-energy state nickel powder obtained by decomposition is easy to sinter and diffuse with elements such as manganese, copper, iron, and aluminum, thus promoting the formation of liquid phase and the sintering process.
Application preparation of nickel carbonate
A method for synthesizing nickel oxide precursor nickel carbonate, the steps are as follows:
1) Cocurrent flow and low pH value synthesis of crude nickel carbonate: Add water to the synthesis tank to immerse the stirring blades, start stirring, slowly introduce steam to raise the temperature to 70~80°C, respectively according to 3m3/h, 2m3/h, add 40g/L nickel sulfate solution and 120g/L sodium carbonate solution in parallel flow, control the pH value of the synthesis end point to 6.9~7.1, and filter to obtain the filtrate and filter cake;
2) Slurrying and high pH alkali leaching desulfurization: Add the filter cake from the previous step into the alkali leaching tank, add water to immerse the stirring blades, start stirring, slowly add steam to raise the temperature to 80~90°C, follow the water, Continue to add water to slurry nickel carbonate in a ratio of 3:1 to the filter cake for 30 minutes. Add 120g/L sodium carbonate solution to adjust the pH to 9.20~9.50. Filter to obtain the filtrate and filter cake. Excess sodium carbonate and nickel carbonate are entrained in the filter cake. SO42- reacts to generate sodium sulfate solution to remove sulfur;
3) Slurrying, washing and sodium removal: Add the filter cake from the previous step into an alkali soaking tank, add water to immerse the stirring blades, start stirring, slowly add steam to raise the temperature to 80~90°C, press water and filter cake 5 Continue to add water to slurry nickel carbonate at a ratio of :1 for 30 minutes, and filter to obtain a filtrate and filter cake. The Na+ entrained in the nickel carbonate filter cake is removed and enters the filtrate.
This method is more traditional than traditional synthesis of high-purity nickel carbonateThis method has absolute advantages, processing costs and investment costs are greatly reduced, and labor productivity is improved. Nickel carbonate synthesis demagnesization can remove 50% magnesium from the supernatant liquid, alkali leaching desulfurization can remove 70% sulfur from the supernatant liquid, and washing desodiumization can remove 70% sodium from the supernatant liquid. Ensure that the total amount of impurities Ca, Mg, S, and Na in high-purity nickel carbonate is ≤0.8%, and the high-purity nickel carbonate reaches the national first-class quality standard for difluoropyridine. The total content of Ca, Mg, S, and Na in nickel oxide is ≤1%, and the quality of nickel oxide products reaches the national quality standard for superior products.
There are few types of chemical reagents, convenient procurement, cheap prices, low processing costs, high metal recovery rates, low equipment material requirements, low investment costs, low technical thresholds, simple and convenient methods, good effects, good quality nickel carbonate, and products The quality is stable and reliable, the processing cost is low, the economy is good, the profit is high, it is convenient for industrial promotion and application, and water resources are recycled. It is a green industrialization project worth promoting with low cost, low energy consumption and high efficiency.
