Preparation and Application of Strontium chloride

Strontium chloride (SrCl2) is a salt composed of strontium and chlorine. It is a typical salt and its aqueous solution is neutral. Similar to other strontium compounds, strontium chloride appears red when burned in a flame, so it is used to make red fireworks. Its chemical properties lie between those of barium chloride (which is more toxic) and calcium chloride. 

Preparation

A method for preparing strontium chloride comprises the following process steps:

1. Mix the lapis lazuli powder with the reduced coal powder in a weight ratio of 1:0.5 to 1:5, and bake them at a temperature of 900 to 1300℃ for 0.5 to 12 hours to obtain black ash. Then, use water to reverse-flow leach the black ash to obtain strontium sulfide solution. The content of strontium sulfate in the lapis lazuli ore is 55 to 100%. The concentration of the strontium sulfide solution obtained by leaching is controlled within 50 to 150 g/L.

2. Pass hydrogen sulfide gas into the strontium sulfide solution, and obtain the strontium hydride sulfide solution.

3. Add magnesium chloride to the strontium hydrosulfide solution and react it at 80-90℃ for 0.5-2 hours. This results in a slurry containing magnesium hydroxide precipitate and a chloride strontium solution, and releases hydrogen sulfide gas. The magnesium chloride used is obtained from salt lake magnesium chloride through conventional purification methods; the amount of magnesium chloride added is 0.85-1.15 times the molar quantity of strontium sulfide.

4. The slurry is subjected to solid-liquid separation to obtain magnesium hydroxide precipitate and strontium chloride solution. The strontium chloride solution is then evaporated, crystallized, separated, and dried to produce strontium chloride product; the magnesium hydroxide is washed and dried to become a by-product; the hydrogen sulfide gas is returned to step 2 and reacts with the strontium sulfide solution to prepare the process of sulfur hydrosulfide.

Purpose

Strontium chloride is the precursor for the production of other strontium compounds, such as strontium chromate. It is used as a corrosion inhibitor for aluminum. The chromate ion is similar to the sulfate ion, and the corresponding precipitation reaction is also similar:

SrCl2 + Na2CrO4 → SrCrO4 + 2 NaCl

Strontium chloride is occasionally used as a red coloring agent for fireworks. Small amounts of strontium chloride are also added in glass manufacturing and metallurgy. The radioactive isotope strontium-89 is used to treat bone cancer and is usually administered in the form of strontium chloride. Marine aquariums require a small amount of strontium chloride to provide certain plankton with the ability to produce exoskeletons.

Tooth care

SrCl2 helps reduce gum sensitivity and periodontal disease. It can be used in the production of toothpaste.