In the in-house alkali extraction tower were technology application research
In in-house alkali extraction tower were research abstract: the application of technology for in-house technical requirements of caustic washing salt process often appear not up to standard, difficult operation and so on, puts forward a new technological process, adopts refined brine secondary washing method, improve the efficiency of ball mill grinding, make the finished products were meet the technical requirements.
crude salt as the main raw material of in-house, in the process of production is a solid form to join the system.
Quality of crude salt producing area is different, also each are not identical, most of the impurities in particle size is bigger and contains calcium, magnesium and sulfate and mud, sand and other impurities.
If a large amount of these impurities be joined together with the crude salt production system, not only affect the quality of the final product, and the volatility of the cause of process operation.
so impurities before joining system, need a refining process (
Include lowering water soluble and water insoluble impurity content and sodium chloride crystal granularity)
As far as possible, make its can satisfy the production requirement, for high quality and high yield of soda ash and chloride in laying a good foundation.
Impurities in the refined evaporation method and two kinds of washing method, evaporation method cost is higher, couplet factory) the washing method is adopted.
In this paper, the method of refining crude salt wash some problems are discussed.
Table 1 is the most united alkali factory were quality specifications.
1 for cutting down the water-soluble impurity 1.
Influence on production 1 water soluble impurities in crude salt common water soluble impurities such as calcium, magnesium and sulfate, the existence of these ions in the system, can cause a series of such as mother liquor turbidity increases, according to the heavy alkali and chloride crystallization and bad for filtration, drying and burning process operations such as satin, affect the quality of the product.
In addition, these ions generated precipitation adhere to the pipe and wall and increase the difficulty of the operation, is the most serious influence effective volume, reduce the production capacity of the equipment.
2 principle of refining crude salt washing method washing salt method is a kind of physical separation of impurities, it is the use of different materials with different solubility properties in the same solvent to separation of impurities.
Soluble impurities in crude salt, magnesium chloride, magnesium sulfate, calcium sulfate micro soluble impurities, etc. , they still has certain soluble in saturated sodium chloride solution, and sodium chloride in the saturated solution is not to dissolve, so using saturated sodium chloride solution as detergent when washing raw salt, so that the impurities such as sodium chloride and magnesium chloride, magnesium sulfate.
Part of mud, sand and weeds and water light person drifting or suspended in liquid detergent, washing liquid is separated from the salt, the person that weigh in mixed with salt, for the subsequent separation process.
3 problems in production in alkali production system, consider two questions: first, the salt leaching process of washing brine is used in continuous closed, along with the continuously of crude salt washing, washing liquid magnesium chloride, magnesium sulfate and other soluble impurities content will also increase gradually, until it is saturated.
At this time of washing brine loses the washing effect of soluble impurities;
Second, in the washing washing brine after a period of time, will change the ingredients.
When several substances exist in the solvent, as a result of the influence of the same ion effect, solubility change, for example, sodium chloride in water solubility is 361.
3 g/h in saturated solubility in the magnesium chloride aqueous solution only 8 g/L in view of the above two situations, production must be continuously excluding some soluble impurities, make its are in a dynamic balance.
The less soluble impurity in brine washing, the washing effect is better also.
Therefore, the secondary brine refining is the best washing liquid.
4 to reduce the water soluble impurities test test process: 1)
Take impurities in that day, and determination of calcium and magnesium content of impurities,
Quality of crude salt)
Take time machine wash finished about 300 g of salt, in about 100 ℃ temperature dry 40 min, the determination of calcium and magnesium content in product of salt (
The quality of salt product)
The rest of the finished product with quadratic saturated salt brine (
In addition to calcium and magnesium after refining brine)
According to the volume ratio 1:1 ratio to wash twice, filtering to dry.
And according to the finished product (dry salt method to determine calcium and magnesium content
Again after washing quality)
Repeat the above operation several times.
the test data, test a set of data are shown in table 2 for many times, it can reflect the effect of refining brine after washing.
5 subtotal 1)
I plant salt leaching technology and the equipment were limited, in our quality is bad, calcium, magnesium, high content of impurities, were produced by it is difficult to meet the technology requirements.
Use my factory production of finished product were quadratic saturated salt water again after washing, salt, calcium and magnesium content of impurities in the finished product meets the technical requirements, technical indexes and magnesium content is much lower than the lowest levels, among them, no matter how the quality of crude salt, with secondary saline wash finished product after salt, lowest ca content were 0.
About 080%, lowest magnesium impurities content in 0.
Considering the cost and quality problems, will make a little improvement of the technological process, our factory were section in part adopts refined brine of salt slurry after washing grinding at the beginning of washing, so, no matter how the quality of crude salt, calcium and magnesium content of impurities will be up to standard, especially the content of magnesium is far lower than the technical indexes.
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