Applications of Potassium Bicarbonate_Industrial Additives

Application background and overview of potassium bicarbonate

Potassium bicarbonate is an important chemical raw material. It is mainly used to produce potassium carbonate, potassium acetate, potassium arsenite, etc., and is also used in medicine, food, fire extinguishing agents and other industries. Potassium salts (K2CO3, KCl, K2SO4, etc.) including potassium bicarbonate are a strategic material and play a vital role in the national economy. However, there are very few exploitable water-soluble potassium salt resource deposits in my country, and the proven reserves only account for 1.06% of the world’s total. At present, my country’s dependence on foreign food-grade potassium bicarbonate is as high as 70%. Therefore, extracting food-grade potassium bicarbonate from alkaline industrial wastewater can alleviate the shortage of potassium salt in my country to a certain extent.

Applied physical and chemical properties of potassium bicarbonate

Food grade potassium bicarbonate is a well-known commodity and has many uses, such as in baking powder, as an effervescent salt in non-alcoholic beverages, as a fire extinguishing agent, and in a variety of pharmaceutical uses, such as treating overdoses acidity. At present, the potassium bicarbonate obtained in large quantities is very fine crystals or agglomerates, which are irregular in shape, rough in surface, poor in filling and fluidity, and prone to dust and caking problems. Food grade potassium bicarbonate has recently been proposed as an active ingredient in the treatment of osteoporosis or hypertension.

Applications of potassium bicarbonate

In recent years, food-grade potassium bicarbonate has been widely used as a food loosening agent and quality improver, and its development has attracted more and more attention. Food-grade potassium bicarbonate is the raw material for the production of food-grade potassium carbonate. Food-grade potassium bicarbonate is widely used in chemical industry, light industry, picture tube glass shells, pharmaceuticals, food, welding rods and non-ferrous metal metallurgy.

Application and preparation of potassium bicarbonate

Method 1:

Step 1, take 5.0kg of alkali zinc carbonate hydroxide liquid wastewater, the K+ concentration is 251.6mg/L (calculated as K2O), the Na+ concentration is 180.0mg/L (calculated as Na2O), and the SiO32- concentration is 30.5mg /L (calculated as SiO2), and the AlO2- concentration is 18.2mg/L (calculated as Al2O3). Under an atmospheric pressure (1.0atm, 101.3kPa), through magnetic stirring, CO2 gas is introduced to acidify the alkali wastewater. When the pH value of the alkali wastewater reaches 7.8-8.2, a white precipitate composed of Si impurity precipitation and Al impurity precipitation appears. Filter and wash with suction, discard the white precipitate, and obtain filtrate A;

In step 2, filtrate A adopts a normal pressure evaporation concentration process. The evaporation temperature is about 100°C. The density of filtrate A changes from 1.05g/cm3 to 1.28g/cm3. When the temperature reaches room temperature, the system crystallizes at room temperature for 2.0h. , a large number of white crystals appear, which are Na2CO3 crystals containing crystal water; Na2CO3 crystals containing crystal water and filtrate B are separated, and the Na2CO3 crystals containing crystal water are calcined at a calcination temperature of 300°C and a time of 2.0 hours to obtain the Na2CO3 product (purity >99.9%, meeting analytical purity requirements);

Step 3. Place filtrate B in an autoclave, add high-pressure CO2, control the pH value of filtrate B at 7.0, the equilibrium pressure P = 0.3MPa, and the crystallization time is 2.0h. At this time, in K-Na- Crystal precipitation also occurs in the HCO3-solution system. The analysis results show that the crystal is KHCO3·xH2O (x=0.5-1.0). It is separated and washed with cold water to obtain refined KHCO3.

Step 4, further evaporate the K ammonium bicarbonate-Na-HCO3- solution obtained in the previous step at 90°C under normal pressure, and the crystallized product obtained is also KHCO3 crystal hydrate; it can also be obtained by filtering, separating and washing with cold water. KHCO3 crystals and filtrate C.

Step 5, combine the refined KHCO3 obtained in steps 3 and 4, and vacuum dry at 80°C for 6 hours to obtain food-grade KHCO3.

In step 6, mix filtrate C with the washing liquid in steps 3 and 4 and add 5.0kg of alkali wastewater in the next round. Repeat the above operation process for five times. Calculate the difference between the product KHCO3 and 25.0kg of raw material. The total amount of potassium in the wastewater alkali solution was compared, and the yield was 90.5%.