Anhydrous calcium chloride preparation system

Abstract

The utility model discloses an anhydrous calcium chloride preparation system which comprises a calcium chloride solution storage tank, a multi-effect evaporator, a freezing crystallization slicing machine, a steel belt furnace and a cooling machine. The method has the advantages that the calcium chloride solution is subjected to solid-liquid separation through the freezing crystallization slicing machine after being concentrated and crystallized in the multi-effect evaporator, crystal water redissolution caused by crystallization heat aggregation can be prevented, then two crystal water and physical moisture in calcium chloride dihydrate are removed through the steel belt furnace, the technological process is simple, continuous production can be achieved, and the production cost is reduced. The industrial grade anhydrous calcium chloride product can be directly prepared. The problems that an atomizer is easy to block and a large amount of dust particles are carried in the dehydrated induced air flue gas when anhydrous calcium chloride is prepared through atomization in the prior art are solved, extra dust recovery is not needed, and the process is simplified.

Description

Technical Field:

[0001] The utility model relates to the technical field of alkaline leaching, and specifically relates to a preparation system for anhydrous calcium chloride. Background Art:

[0002] The process of recovering valuable metals from solid wastes such as electrolytes, carbon residues, and overhaul residues in aluminum electrolysis plants by alkaline leaching mainly uses carbide slag (the main component is Ca(OH) 2 ) to leach valuable metals such as Li, Na, K, etc. in solid wastes such as electrolytes, carbon residues, and overhaul residues by alkaline leaching, and finally recovers them through further treatment; the Ca ions introduced in this process will finally dissolve in the solution in the form of CaCL 2 .

[0003] CaCl 2 is a large and medium-sized chemical product with relatively high utilization value. Therefore, preparing the CaCL 2 in the solution (in addition to anhydrous calcium chloride, there are also hexahydrate, tetrahydrate, dihydrate, and monohydrate) into anhydrous calcium chloride for sale can not only effectively recover Ca but also greatly increase the economic benefits of by-products, which plays a good role in reducing production costs.

[0004] Most of the existing processes for preparing anhydrous calcium chloride first evaporate and concentrate the calcium chloride concentration to 50%, then enter the atomizer through an atomizing pump, atomize and enter the fluidized bed drying granulator (while introducing hot air for dehydration), granulate and then cool and package; however, there is a problem that the atomizer is easily blocked, and moreover, a large amount of dust particles are entrained in the induced draft flue gas after dehydration and need to be dust-removed. The collected dust particles need to be returned to the atomizing pump, resulting in disadvantages such as repeated circulation, doing a lot of useless work, and wasting energy. Content of the Utility Model:

[0005] The purpose of the utility model is to provide a preparation system for anhydrous calcium chloride.

[0006] The utility model is implemented by the following technical solution: A preparation system for anhydrous calcium chloride, characterized in that it includes a calcium chloride solution storage tank, a multi-effect evaporator, a freezing crystallization slicer, a steel belt furnace, and a cooler. The outlet of the calcium chloride solution storage tank is communicated with the inlet of the multi-effect evaporator, the concentrated solution outlet of the multi-effect evaporator is communicated with the inlet of the freezing crystallization slicer, the solid outlet of the freezing crystallization slicer is communicated with the inlet of the steel belt furnace, and the outlet of the steel belt furnace is communicated with the inlet of the cooler.

[0007] Further, the mother liquor outlet of the freezing crystallization slicer is communicated with the inlet of the calcium chloride solution storage tank.

[0008] Further, the multi-effect evaporator includes a double-effect evaporator and a single-effect evaporator connected in sequence.

[0009] Further, the outlet of the calcium chloride solution storage tank is communicated with the second-effect inlet of the double-effect evaporator, and the first-effect outlet of the double-effect evaporator is communicated with the inlet of the single-effect evaporator.

[0010] Further, the cooler is a double-screw cooler.

[0011] Advantages of the present utility model: After the calcium chloride solution is concentrated and crystallized in the multi-effect evaporator, solid-liquid separation is carried out by a freezing crystallization slicing machine, which can prevent the re-dissolution of crystal water caused by the aggregation of crystallization heat. Then, a steel belt furnace is used to remove 2 crystal waters and physical moisture in the calcium chloride dihydrate. The process flow is simple, continuous production can be realized, and industrial-grade anhydrous calcium chloride products can be directly obtained. It avoids the problems that the atomizer is easily blocked and a large amount of dust particles are entrained in the induced draft flue gas after dehydration in the conventional atomization method for producing anhydrous calcium chloride, and there is no need for additional dust recovery, which simplifies the process. Description of the drawings:

[0012] Figure 1 It is the overall structure diagram of the present utility model.

[0013] Calcium chloride solution storage tank 1, multi-effect evaporator 2, double-effect evaporator 21, single-effect evaporator 22, freezing crystallization slicing machine 3, steel belt furnace 4, cooler 5. Specific embodiments:

[0014] In the description of the present utility model, it should be noted that when terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. appear, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, so it cannot be understood as a limitation to the present utility model. In addition, when terms such as "first", "second", "third" appear, they are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0015] Such as Figure 1As shown in the figure, an anhydrous calcium chloride preparation system includes a calcium chloride solution storage tank 1, a multi-effect evaporator 2, a freezing crystallization slicer 3, a steel belt furnace 4, and a cooler 5. The outlet of the calcium chloride solution storage tank 1 is communicated with the inlet of the multi-effect evaporator 2. The concentrated solution outlet of the multi-effect evaporator 2 is communicated with the inlet of the freezing crystallization slicer 3. The mother liquor outlet of the freezing crystallization slicer 3 is communicated with the inlet of the calcium chloride solution storage tank 1. The solid outlet of the freezing crystallization slicer 3 is communicated with the inlet of the steel belt furnace 4. The outlet of the steel belt furnace 4 is communicated with the inlet of the cooler 5. In this embodiment, the multi-effect evaporator 2 includes a double-effect evaporator 21 and a single-effect evaporator 22 connected in sequence. The outlet of the calcium chloride solution storage tank 1 is communicated with the second-effect inlet of the double-effect evaporator 21. The first-effect outlet of the double-effect evaporator 21 is communicated with the inlet of the single-effect evaporator 22. The cooler 5 is a double-helix cooler 5.

[0016] Preparation process:

[0017] S1: The solution with a calcium chloride concentration of 10%-30% obtained by leaching calcium from solid wastes such as electrolytes, carbon slag, and overhaul slag in an aluminum electrolysis plant is stored in the calcium chloride solution storage tank 1 and then sent to the multi-effect evaporator 2 for concentration. Specifically, it is first sent to the double-effect evaporator 21. After the calcium chloride concentration is concentrated to 39% by second-effect evaporation, it is then concentrated to 55% by first-effect evaporation. Then it is sent to the single-effect evaporator 22 for concentration to obtain a concentrated solution of calcium chloride dihydrate with a concentration of 75%.

[0018] S2: To avoid the recrystallization of crystal water due to the accumulation of crystallization heat, the concentrated solution of calcium chloride dihydrate with a concentration of 75% obtained in S1 is pumped into the freezing crystallization slicer 3 for liquid-solid separation to obtain calcium chloride dihydrate solids and separated mother liquor.

[0019] S3: The separated mother liquor obtained in S2 is sent back to the calcium chloride solution storage tank 1 for re-concentration.

[0020] S4: The calcium chloride dihydrate solids obtained in S2 are added to the steel belt furnace 4 and calcined at a high temperature of 260-350°C to remove 2 crystal waters and physical water in the calcium chloride dihydrate. Then it is sent to the double-helix cooler 5 to cool down to 40-60°C to obtain a 94% industrial-grade anhydrous calcium chloride product.

[0021] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for preparing anhydrous calcium chloride, characterized in that: It comprises a calcium chloride solution storage tank, a multiple-effect evaporator, a freezing crystallization slicer, a steel belt furnace and a cooler, wherein the outlet of the calcium chloride solution storage tank is connected to the inlet of the multiple-effect evaporator, the concentrated solution outlet of the multiple-effect evaporator is connected to the inlet of the freezing crystallization slicer, the solid outlet of the freezing crystallization slicer is connected to the inlet of the steel belt furnace, and the outlet of the steel belt furnace is connected to the inlet of the cooler.

2. A system for preparing anhydrous calcium chloride according to claim 1, characterized in that, The mother liquor outlet of the freezing crystallization microtome is communicated with the inlet of the calcium chloride solution storage tank.

3. A system for preparing anhydrous calcium chloride according to claim 1 or 2, characterized in that, The multi-effect evaporator comprises a double-effect evaporator and a single-effect evaporator which are connected in sequence.

4. A system for preparing anhydrous calcium chloride according to claim 3, characterized in that, The outlet of the calcium chloride solution storage tank is communicated with the second effect inlet of the double-effect evaporator, and the first effect outlet of the double-effect evaporator is communicated with the inlet of the single-effect evaporator.

5. A system for preparing anhydrous calcium chloride according to claim 1, characterized in that, The cooler is a double-screw cooler.

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