Wine Stone

Tartar, potassium hydrotartrate, potassium sour tartaric acid, cremartartar, crystalline sediment falling and deposited on the bottom and walls of winemaking containers during alcoholic fermentation of grape must, aging and processing of wine.
It is a valuable raw material for the production of tartaric acid. In grape juice, tartar is found in a dissolved state, and a saturated solution is formed in wine. Loss of tartar occurs under the influence of mechanical stress (agitation or jolts), with an increase in alcoholism or with a decrease in temperature. Small crystals can fall out even in the finished bottled wine, so the wine is cold before bottling and kept at a temperature close to its freezing point. Tartar consists mainly of potassium bitartrate (KNS4NH) 6) and calcium tartrate (CaC4H406. 4H2O). Dropping out of wine, tartrate compounds entrain yeast cells, dyes, silica, salts of iron, ammonium and other impurities in the wine. Depending on the presence of these impurities, tartar contains from 50 to 70% tartaric acid, and sometimes more. The following chemical composition of tartar is typical (%): bitartrate (potassium sour tartrate) - 82.95; calcium tartrate - 5.4; silica - 1,1; magnesium oxide - 0.9; alumina - 0.92; organic matter - 6.2; other substances - 2.53.
 According to the formula, 79.75% tartaric acid may be contained in a chemically pure tartar. The taste of tartar is slightly acidic, the color is white. In dry form, is a persistent product. With strong heating decomposes, the residue after calcination consists of potash. Tartar solutions very quickly become covered with mold, decomposing it. It is soluble in hot water, poorly in cold, insoluble in alcohol. Tartar dissociation constant: K = 4.5. 10 ~ 5. In water-alcohol solutions, its solubility decreases with increasing alcohol content. With a wine strength of 10-20% vol. Tartar solubility is reduced by about 50% against its solubility in water.
ways the tartar is extracted mechanical and chemical. With the mechanical method, the bottom of the barrel is opened and tartar crystals are beaten off with sharp hammers (texels) or removed by curving cooper strings. From the bottles and cisterns of tartar are removed, heating the walls with a blowtorch. Raw tartar is washed with cold water and dried after decanting.
 In the chemical method of extracting tartar, barrels, bottles, tanks and reinforced concrete tanks are washed with a solution of soda or mineral acid (sulfuric, hydrochloric).
 In the soda method, a hot solution of soda ash is prepared at the rate of 250 g of soda per 1 dal of water, or the soda is supplied directly to the container along with hot water and steam. From the obtained hot tartrate solution spend the precipitation of tartrate lime calcium chloride. In the acid method, a 2% solution of sulfuric acid or a 3% solution of hydrochloric acid is usually used. Merged wash liquid is treated with milk of lime with the addition of calcium chloride to slightly acidic reaction. The result is a precipitate of tartrate lime. Upon receipt of the vacuum wort grape tartar in a hot solution is in a supersaturated state. When the wort cools down, the tartar goes into sediment. It is then separated, washed 3-4 times with cold water and dried. Such tartar is the richest tartaric acid raw material with tartaric acid content up to 75%. Dried tartar is collected separately from tartrate lime in Kraft bags, which are sewn up, labeled, and after being weighed by motor transport or in railway cars, are sent to tartaric acid production plants.