In order to take full advantage of waste electrolyte co-produced by the magnesium refining from the carnallite and comprehensively utilize the magnesium resources in the salt lakes in Qinghai province,the production process of synthetic carnallite with adding brine cold-crystallization method was developed.

1% could be got from separation salt by adding brine crystallization method.

When producing carnallite by mixing brine,the old brine composition can influence the production index,including per unit yield and productivity of carnallite and the content of sodium chloride,in the solid of mixing brine.

During carnallite was produced by mixing brine in the salt lake,the temperature influenced the production index in the solid produced by mixing brine,including the productivity of carnallite,perunit yield of carnallite and content of sodium chloride and so on.

The technological process and principles of potassium chloride production method by mixing brine are introduced in the paper.

By determining the water of salt pond in Guanxi saltern, Jiangsu province, We found　that the basic nutritive material and PH were fit for the algae growth.

The influence of adding brine ratio on the recovery rate of the potassium chloride in the KCl production process by adding brine method;