Food Grade Phosphoric Acid

1.Improve the flavor of refreshing drinks. In carbonated drinks, it can interact with metal ions in water to from soluble salts, block the activity of metal ions, so as to prevent the beverage from oxidation, deterioration and color change. It can also make the drinks stable for a long time.
2.Used in fruit juice beverages to keep Vitamin C stable. In the case of vitamin C fortification, the addition of phosphate can effectively prevent the oxidative decomposition of vitamin C, as well as stabilize the juice suspension. Meanwhile, food grade phosphoric acid can prevent soluble pectin from becoming insoluble pectin when soluble pectin adjusts the specific gravity of the concentrated juice slurry.
3.The use of phosphoric acid in the crushing process of fruit juice can prevent the flavor of pulp from being broken due to rapid oxidation and discoloration.
4.Prevent fruit precipitation after crushing ans clarification and prevent the change of color.
5.Adding 0.1% to 0.3% of phosphates in sherbet can prevent the change of color and flavor oxidation.

Phosphorus is an essential trace element for the human body. When the ration of calcium to phosphorus in the human blood is 2:1, it can also promote the absorption of calcium by the human body. After the phosphorus is absorbed by the human body, it will exist in the human bones and teeth in the form of phosphate. Phosphoric acid added to the beverage is food grade, only drinking phosphorus-containing beverages in excess will cause harm to human body.

Food grade phosphoric acid in drinking beverages will reduce the absorption of calcium in the body and affect the normal growth of bone. Children and adolescents who are in the period of growth and development need sufficient calcium to enable normal bone growth and development, maintain good bone metabolism and achieve optimal bone density, so it is more inappropriate to drink carbonated drinks. In addition, phosphoric acid can also hinder the absorption of iron, which is one of the main materials for making blood. Once the iron isn’t enough, it can cause iron deficiency anemia.

It is in colorless, transparent or slightly light color thick liquid. It is odorless and tastes very sour. Phosphoric acid has the melting point of 42℃ and the boiling point of 261℃. It dehydrates gradually when it is heated. It belongs to RO-PO and the crystallization point is 21℃. Like other liquid crystallization, phosphate crystallization is physical changes rather than chemical changes. So its chemical property won’t change because of crystallization. It can be used normally as long as it is heated to melt. Food grade phosphoric acid has the features of high concentration, high purity and high crystallinity. When the temperature is around 4℃ and the concentration is larger than 85%, the crystallinity will increase. If the chemical is accidentally mixed with crystalline phosphoric acid, the original phosphoric acid that hasn’t crystallized will be crystallized immediately and the phosphoric acid in storage container will be crystallized abnormally rapidly. After the phosphoric acid crystallizes, the upper phosphoric acid becomes dilute and the needle-like crystal pure phosphoric acid food grade is deposited in the lower part.

Thermal Method

The production of food grade phosphoric acid is usually adopts thermal production process, which can produce the pure phosphoric acid with less metal and impurities. The process of thermal phosphoric acid mainly uses the yellow phosphorus produced by electrothermal process as raw material, then through combustion and hydration, and make phosphoric acid 85 food grade.

The Production Process of Hydrochloric Acid Method

1.Preparation of raw materials. Pulverized ore-rich ore containing P2O5>5wt% as raw material, crushed to more than 20 mesh to form phosphate ore powder.

2.Acid hydrolysis. Under stirring conditions, the prepared phosphate rock powder is acid hydrolyzed with 15wt%~35wt% hydrochloric acid, and the molar ratio of hydrochloric acid is that the calcium in the phosphate rock powder is completely converted into hydrogen chloride required for calcium chloride 95%～110% of theoretical dosage, acid hydrolysis reaction time is 15～45 minutes.

3.Pre-doping. Add 6wt%～12wt% Na2S solution to the process liquid after acid hydrolysis, the amount of Na2S solution is 2% to 4% of the volume of the process liquid.

4.Filtration. Add flocculant to the process liquid after removing impurities to flocculate and precipitate, obtain the desired filtrate after filtration.

5.Extract iron removal. Extract the filtrate by extraction, the extractant is subjected to countercurrent extraction and composed of N235, isooctyl alcohol and kerosene. The ratio of the extractant to the filtrate is 1:1, the extraction temperature is 15 to 45°C, and the residual water phase is iron-removed dilute phosphoric acid.

6.Extraction. A mixed solvent of tributyl phosphate and kerosene is used as an extractant to perform at least ten-stage extraction of the iron-removing dilute phosphoric acid. The volume ratio of kerosene and tributyl phosphate is 1:1~2, and the extraction temperature is 15~45℃, phosphoric acid in the process liquid enters the organic phase after extraction. The impurities and free hydrochloric acid remain in the aqueous phase. The volume ratio of the aqueous phase and the extraction phase is 1:3 to 5.

7.Washing. The organic phase after extraction shall be washed by 10wt%~18wt% dilute phosphoric acid solution in at least five stages. During washing, the volume ratio of water phase and organic phase is 1:20-30.

8.Back extraction. Use 0.5wt%~1.5wt% dilute hydrochloric acid to extract the organic phase at least five levels. During the back-extraction, the ratio of water phase and organic phase is 1:10～15, and the water phase after back-extraction is dilute phosphoric acid.

9.Removal of impurities. Na2S solution was added into the dilute phosphoric acid produced by reverse extraction for secondary impurity removal and adsorption by activated carbon, and then filtrated by precision filter.

10.Oxidation. Add hydrogen peroxide to remove easy oxides contained in dilute phosphoric acid.

11.Evaporation and concentration. The oxidized dilute phosphoric acid was preheated, and the phosphoric acid containing more than 475wt % H3PO475 was obtained after evaporation and concentration. The evaporated hydrochloric acid was recovered and returned to step two for acid dissolution.

12.Decolorization and filtration. The concentrated Phosphoric acid is cooled, and activated carbon is decolorized and filtered to obtain food grade phosphoric acid.