CN1304295C - Method of producing iporganic strontium salt by using high barium high calcium celestine - Google Patents

Abstract

The invention relates to a method for producing strontium inorganic salt from high-barium and high-calcium celestite, which is characterized in that: a solvent extraction method is used to purify and separate the strontium sulfide solution obtained by immersing celestite black ash in water. The selected extraction agent and extraction method can adapt to the strong alkalinity of the strontium sulfide solution, and can be directly extracted in the alkaline strontium sulfide solution. After multi-stage countercurrent extraction, control the extraction balance of calcium, strontium and barium, combined with reflux washing and step-by-step stripping, the strontium and separated barium products can reach the desired purity, which is used to produce strontium nitrate, strontium chloride, General and high-purity inorganic salt products such as strontium carbonate or strontium oxide.

Description

Method for producing strontium inorganic salt by utilizing high barium and high calcium celestite

Technical field Inorganic chemical industry.

Background Art Strontium carbonate is an important chemical product, mainly used in fluorescent screen glass, magnetic materials, and ceramics. my country is rich in mineral resources and is one of the main producers and exporters of strontium salts and oxides in the world. Celestite is a sulfate of strontium and is its most important mineral.

The most widely used method for producing strontium from celestite is the reduction method. The basic process of the reduction method is to react with celestite with a gas or solid reducing agent for 8 to 10 hours at a high temperature of 1100-1200 ° C, so that the strontium sulfate in it is reduced to strontium sulfide (often called "black ash"). Then soak strontium sulfide in hot water to dissolve it in water to form a solution of strontium sulfide, strontium hydrosulfide and strontium hydroxide, which is collectively referred to as strontium sulfide solution hereinafter. Then the strontium sulfide solution is further processed into other strontium products, such as strontium carbonate.

The process of this method is simple, the sulfur is better utilized, and the economic benefit is good. The disadvantage is that high-temperature reduction produces sulfide tail gas, and if the sulfur-containing wastewater is not treated properly, it will cause serious pollution; moreover, there is no effective purification method, and the product quality is limited.

Since strontium and barium are substituted for each other in the ore, after the ore is reduced, the strontium salt solution obtained by leaching contains a certain amount of barium, and often also contains a certain amount of calcium. Due to the lack of effective separation methods for strontium, barium and calcium, the current production plants use ore raw materials with low impurities to ensure the quality of products. With the expansion of production scale and the gradual consumption of high-quality ores, production plants are faced with the problem of using ores with high impurity content, especially celestite with high calcium and barium content.

Strontium and barium have similar chemical properties, and the solubility of common insoluble salts such as sulfate, carbonate, and oxalate is not much different, because the separation coefficient between these elements is very low. Therefore, when one element is the main component, the concentration is high, while the other is the impurity component, the concentration must be relatively low. The precipitation reactions of strontium ions and barium ions are all ionic reactions, and the speed is extremely fast. When removing impurities by precipitation, the main components are often lost greatly, while the impurities fail to meet the requirements. That is to say, in order to ensure the recovery rate, the impurities cannot be removed deeply. It is for this reason that so far, manufacturers have been reluctant to use lapis lazuli with poor grade and high impurities as raw materials.

The solvent extraction process is a reversible reaction, usually done by multi-stage countercurrent. Therefore, when the impurities and the main components are separated, they are continuously exchanged from one level to another, which can not only achieve a high separation coefficient, but also ensure a high recovery rate, and is especially suitable for the separation and recovery of components with similar properties. . It has been widely used in the separation and purification of non-ferrous, rare, rare earth and precious metals in the metallurgical industry. The technology is mature, the operation cost is low, and it is suitable for large-scale production.

Contents of the invention

(1) The solvent extraction process is a reversible reaction. Through multi-stage countercurrent, impurities and main components are continuously exchanged from one stage to another when they are separated, which can not only achieve a high separation coefficient, but also ensure a high The recovery rate, combined with washing and stripping under controlled conditions, separates the strontium and barium in the solution from each other. Due to the strong alkalinity of strontium sulfide solution, the extraction research in this kind of solution is rarely reported, and there is no patent, which is different from the law and process of extraction and separation from neutral solutions such as strontium chloride or strontium nitrate. very big. The extractant used must be alkali-resistant and have little solubility in alkaline aqueous solution. By controlling the extraction balance of calcium, strontium and barium step by step, the invented process can reduce impurities such as calcium to the design level, so that both strontium and separated barium products can reach the purity stipulated by the national standard.

(2) Ordinary strontium or barium sulfide solution is used as raw material, using solvent extraction method, through multi-stage countercurrent extraction, by controlling the extraction balance of calcium, strontium and barium, combined with reflux washing and step-by-step back extraction, refining, producing high-quality Pure strontium carbonate, strontium nitrate, strontium chloride or strontium oxide and other inorganic salt products.

(3) The used extraction agent of aforementioned (1) and (2) extraction method is: the fatty acid of 7～15 carbons, the naphthenic acid of 8～18 carbons, 2-ethylhexylphosphonic acid-2-ethylhexyl ester, Di(2,4,4-trimethylpentyl)phosphonic acid, trialkylphosphine oxide and trimethyloctylamine chloride.

(4) The aforementioned (1) and (2) extraction, washing and stripping all adopt the countercurrent method, the volume concentration of the extractant and the two-phase flow ratio are different according to the content of barium and calcium in the lapis lazuli, and the concentration of the extractant is different. Volume concentration is generally 5% to 50%; extraction flow ratio: organic phase: water phase = 5 to 1, residence time 1 to 40min; detergent is hydrochloric acid or nitric acid solution, concentration 1% to 5%, washing flow ratio: organic Phase: water phase=3～1; stripping agent is hydrochloric acid or nitric acid solution, concentration 5%～25%, stripping flow ratio: organic phase: water phase=10～1.

The effect of the invention

(1) By adopting the solvent extraction and purification process of the present invention, the impurities in the strontium sulfide solution containing very high barium and calcium can be reduced to the desired level. When the initial strontium sulfide solution contains strontium 50-140g/L, barium 5-10g/L, and calcium 2-10g/L, after extraction, the barium is less than 0.5-1g/L, and the calcium is less than 0.2-1g/L. It can be used to produce national standard first-class or superior strontium carbonate. And after washing and step-by-step stripping, the obtained barium solution can also be used to produce qualified barium products, so that the components that are originally impurities can be recovered and utilized.

(2) Adopting the solvent extraction and refining process of the present invention, the strontium sulfide solution of general purity can be refined through countercurrent extraction, reflux washing and stepwise stripping. When the initial feed liquid contains strontium concentration of about 50g/L, it contains about 1g/L of barium, calcium and other impurities. After extraction and refining, the concentration of impurities such as barium and calcium can be reduced to 5-50mg/L. It can be used to produce strontium carbonate, strontium nitrate, strontium chloride or strontium oxide, and the final product has a purity of 99.9% to 99.99%.

Example

Example 1.

Separation and purification of high barium and high calcium strontium sulfide solution. The raw material strontium sulfide solution concentration Sr52.9g/L, Ba concentration 5.8g/L, Ca concentration 2.8g/L. 2-ethylhexylphosphonic acid-2-ethylhexyl ester extractant with a volume concentration of 25% was used as the organic phase, and 10% HCl was used as the stripping agent. The test device is a small pulse packed tower. Extraction flow ratio: organic phase: water phase = 3:1. Stripping flow ratio: organic phase: water phase = 5:1. All operations were performed at room temperature. The strontium chloride solution obtained by stripping contains 217g/L of SrCl ₂ , 1.8g/L of Ba concentration, and 0.67g/L of Ca concentration, which meets the requirements of the national standard for producing first-class strontium chloride. The obtained barium sulfide solution contains _about 6g/L of BaCl, 0.27g/L of Sr concentration, and 0.0061g/L of Ca concentration, which meets the requirements for the production of first-class barium carbonate according to the national standard.

Example 2.

High-purity strontium salt was prepared from ordinary strontium sulfide solution. The raw material strontium sulfide solution had a Sr concentration of 42.7g/L, a Ba concentration of 4.8g/L, a Ca concentration of 2.8g/L, and a Na concentration of 6.8g/L. Bis(2,4,4-trimethylpentyl)phosphonic acid extractant with a volume concentration of 25% was used as the organic phase. The test device is a small pulse packed tower. The extraction flow ratio is organic phase:water phase=3:1. The detergent is 1% HCl, and the washing flow ratio is organic phase:water phase=3:1. The stripping agent is 10% HCl, and the stripping flow ratio is organic phase:water phase=8.5:1. All operations were carried out at room temperature. Back extraction gained strontium chloride solution, Sr concentration 120g/L, Ba concentration＜0.02g/L, Ca concentration＜0.02g/L, Na concentration＜0.01g/L, heavy metal (calculated as Fe)＜0.001g/L. Suitable for the preparation of high-purity strontium salt.

Claims (1)

1. A method utilizing high-barium high-calcium celestite to produce strontium inorganic salt is characterized in that: the strontium sulfide solution obtained by solvent extraction method purification and separation of celestite black ash water immersion, the extraction agent and extraction method selected can To adapt to the strong alkalinity of the strontium sulfide solution, extract directly in the alkaline strontium sulfide solution, combine washing and stripping, and refine. The specific measures of the method are as follows: (1) The volume concentration and the two-phase flow ratio of the extractant vary according to the content of celestite strontium and calcium, and the volume concentration of the extractant is 5% to 50%; the extraction flow ratio: organic phase: water phase=5～1 , the residence time is 1 to 40 minutes; (2) The detergent used for washing is hydrochloric acid or nitric acid solution, concentration 1%～5%, washing flow ratio: organic phase: water phase=3～1; (3) The used stripping agent of stripping is hydrochloric acid or nitric acid solution, concentration 5%～25%, stripping flow ratio: organic phase: aqueous phase=10～1; The extractant used is: fatty acid with 7-15 carbons, naphthenic acid with 8-18 carbons, 2-ethylhexylphosphonic acid-2-ethylhexyl ester, di(2,4,4-trimethylpentyl ) phosphonic acid, trialkylphosphine oxide and trimethyloctylammonium chloride.