The basic principle of carbonization is to carbonize the organic matter in the waste salt at low temperature, and then separate the carbon salt, so as to remove the organic matter in the waste salt. This method has different possible system configurations, and parameters such as the selection of carbonization equipment, process route, carbonization
temperature and time can be adjusted according to the technical requirements.
Single-stage carbonization process can be used for waste salt with single component and low organic content.First, the waste salt is dried and dewatered to form particles with good fluidity, and then mixed with the flowing hot air in the carbonization furnace, so that the organic matter in the waste salt forms volatile matter and organic carbon in a
low oxygen atmosphere. Then the salt and organic carbon mixture can be further treated as needed, such as by dissolution,filtration, crystallization, etc.
Multi-stage carbonization process can be used for industrial waste salt with high organic matter content. Due to the presence of more organic matter and many substances with low melting point, if single-stage carbonization were to be adopted, the carbonization process of organic matter would be short, and the carbonization condition is not
sufficient；should the temperature is raised, the waste salt easily softens, resulting in material bonding and blockage of the equipment. Multi-stage carbonization means that the organic matter with different melting point or decomposition temperature is carbonized step by step under different temperature conditions. Through this step-by-step deep
carbonization, the organic matter can be removed completely, and problems such as melting and bonding of waste salt can be avoided.
The phase diagram of water-salt system is a diagram，of to show the phase equilibrium of the water-salt system,and it is one of the important theoretical basis of the inorganic chemical industry. The phase diagram can be used to analyze the various changes and limitations that will occur in the system as a result of changes in external conditions,
and the precipitation sequence of each salt in the system as well as changes in solubility with changes in temperature can be predicted. By applying the rules given by the phase diagram and changing the external conditions of the system,some salts we want can be crystallized and precipitated from the solution, and other salts can be dissolved, thus the
separation can be realized. Using the phase diagram of water-salt system to carry out inorganic salt phase separation lowers chemical consumption, lowers equipment consumption and lowers energy consumption, etc. Separate crystallization technologies that have been realized: sodium sulfate and sodium chloride, magnesium sulfate and sodium chloride, calcium chloride and sodium chloride, sodium chloride and ammonium chloride, potassium chloride and sodium chloride, potassium nitrate and ammonium chloride, magnesium chloride and sodium chloride…