Sodium-strontium-carbonate-water

In another process, strontium sulfate can be converted to strontium carbonate direcdy by a metathesis reaction wherein strontium sulfate is added to a solution of sodium carbonate to produce strontium carbonate and leave sodium sulfate in solution (6). Prior to this reaction, the finely ground ore is mixed with hydrochloric acid to convert the calcium carbonates and iron oxides to water-soluble chlorides. 

Strontium carbonate is insoluble in water. It precipitates from the product mixture in the second reaction. If fused with sodium carbonate, the product mixture is leached with water. Insoluble carbonate separates from the water-soluble sodium sulfate. 

High-gravity reactive precipitation (HGRP) has been extended to the production of aluminum hydroxide and strontium carbonate (57). Aluminum hydroxide fibrils precipitate from the reaction of sodium meta-aluminate (NaA102), water, and carbon dioxide and are formed in diameters of 1-10 nm and lengths of 50-300 nm. Rotor speed, gas- and liquid-flow rates, and initial reactant concentrations control particle size. Strontium carbonate particles of 40-nm mean diameter and narrow size distribution have been produced from the liquid-liquid reaction of strontium nitrate and sodium carbonate. 

The method consists in first converting the sulphate into the carbonate by boiling it with a concentrated solution of sodium carbonate, and then dissolving the carbonate in hydrochloric acid, thereby yielding a solution of the chloride. The conversion of solid strontium sulphate into solid strontium carbonate furnishes an interesting illustration of the solubility product principle, for the solubility of these two salts in pure water is as follows ... 

Strontium sulphate would dissolve in the solution of sodium carbonate in the same manner as it would in pure water until it had saturated the solution, and its solubility product, which is equal to 0.0006 X 0.0006, was reached, but for the fact that long before this could occur the solution would be supersaturated with respect to strontium carbonate, the solubility product of which is only equal to 0.00007 X 0.00007. Thus strontium carbonate is precipitated continuously as strontium sulphate dissolves and since the solution cannot become saturated with the latter as long as a large excess of carbonate ions is present, the solid salt finally remaining will consist entirely of strontium carbonate, provided a sufficient amount of sodium carbonate were employed. The reaction which takes place is, however, reversible, SrSO + Na2C03 SrCOj + NasSO, and, if strontium carbonate were boiled with a solution of sodium sulphate, the solid would change into sulphate until carbonate ions had accumulated in the solution to such an extent as to make the concentration ratio [C03 ] [SO4 ] = 1 74. When this ratio prevails, both solids are in equilibrium with the solution and no change takes place in either direction. 

Manufacture. Strontium carbonate occurs naturally as a strontium ore, but the production is not large. Celestine(consisting mainly of SrSO and containing Ca and Ba) is heated with sodium carbonate to form a melt, and the product is then washed with water to remove the strontium sulphate. 

In addition, precipitation of fission-product elements has been demonstrated. The addition of sodium carbonate or sodium sulfate to molten equimolar sodium-potassium nitrate containing soluble strontium nitrate results in precipitation of strontium carbonate or strontium sulfate, respectively. Molybdenum trioxide, M0O3, added to an equimolar sodium-potassium nitrate melt resulted in evolution of nitrogen dioxide and dissolution of the molybdenum, presumably as the molybdate anion, MogOy (14). Addition of soluble strontium nitrate to this nitrate melt produced an insoluble precipitate that was also insoluble in water. The existence of an aqueous insoluble strontium molybdate is known, and it is believed that a similar species is formed in the melt. 

Evaporate the filtrate of the second barium precipitate to roughly 5 mJ and then dilute to approximately 25 ml with water. Precipitate strontium as strontium carbonate using 10 % sodium carbonate solution. Centrifuge off the strontium carbonate precipitate, pour off the mother liquor above it, cause the precipitate to swirl up with 10 % Na2C03 and centrifuge again. 

After mining, the raw ore is finely crushed and ground and undergoes a froth flotation ben-eficiation process to concentrate and separate celestine from byproduct minerals (e.g., barite). Then, the concentrate ore is reduced by pyrolysis in a kiln to strontium sulfide (i.e., SrS or black ash). The black ash is then dissolved in pure water, and the aqueous solution is treated with sodium carbonate to precipitate the strontium-carbonate crystals. After the strontianite crystals are removed and dried, the strontianite undergoes a calcination, evolving carbon dioxide and giving anhydrous strontium oxide (i.e., SrO, strontia). Strontium metal can be obtained either by thermal reduction of this strontium oxide with molten aluminum in a vacuum or by fused strontium chloride electrolysis. 

Uranium mineral first is digested with hot nitric acid. AH uranium and radium compounds dissolve in the acid. The solution is filtered to separate insoluble residues. The acid extract is then treated with sulfate ions to separate radium sulfate, which is co-precipitated with the sulfates of barium, strontium, calcium, and lead. The precipitate is boiled in an aqueous solution of sodium chloride or sodium hydroxide to form water-soluble salts. The solution is filtered and the residue containing radium is washed with boiling water. This residue also contains sulfates of other alkahne earth metals. The sohd sulfate mixture of radium and other alkahne earth metals is fused with sodium carbonate to convert these metals into carbonates. Treatment with hydrochloric acid converts radium and other carbonates into chlorides, all of which are water-soluble. Radium is separated from this solution as its chloride salt by fractional crystallization. Much of the barium, chemically similar to radium, is removed at this stage. Final separation is carried out by treating radium chloride with hydrobromic acid and isolating the bromide by fractional crystallization. 

If one brings into the flame of the spectroscope a drop of mother liquor from the Durkheim mineial water, one recognizes only the characteristic rays of sodium, potassium, lithium, calcium, and strontium If then, after having precipitated by known methods the lime, strontia, and magnesia, one takes up the residue with alcohol previously treated with nitric acid to fix the bases, one obtains, after having removed the hthia by means of ammonium carbonate, a mother liquor which in the spectroscope gives the lines of sodium, potassium, and lithium, and, m addition, two remarkable blue lines, very close together, one of which coincides almost exactly with the line Sr S. 

Cse TUn and rubidium.—R. Bunsen and G. Kirchhoff (I860),11 while investigating the mineral waters of Durkein (Palatinate), evaporated down 40 tons of the water, and removed the alkaline earths, and lithia with ammonium carbonate. The filtrate showed the spectral lines of sodium, potassium, and lithium, and besides these, two splendid blue lines near to the blue strontium line. R. Bunsen aud G. Kirchhoff add ... 

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