Crystallization system for preparing borax from salt lake brine

Abstract

The utility model relates to the technical field of salt lake boron resources, and particularly discloses a crystallization system for preparing borax from salt lake brine, which comprises a first hot melting batching tank, a second hot melting batching tank, a first set of crystallization tank, a second set of crystallization tank, a buffer tank and a centrifugal machine, the first crystallization tank comprises a first crystallization tank, a second crystallization tank, a third crystallization tank and a fourth crystallization tank, the second crystallization tank comprises a fifth crystallization tank, a sixth crystallization tank, a seventh crystallization tank and an eighth crystallization tank, the first hot melting batching tank collects borax mother liquor, and the borax mother liquor is mixed with a surface active additive and then enters the first crystallization tank in sequence; after the first set of crystallizing tank is cooled to a certain temperature, the materials enter a second hot-melting batching tank in a manner of introducing the discharged materials into a groove, and the materials in the second hot-melting batching tank are sequentially pumped into the second set of crystallizing tank through a pump, are continuously cooled to a certain temperature, enter a buffer tank and then enter a centrifugal machine to be separated; according to the utility model, accurate temperature and time control is carried out on two-stage cooling crystallization, and the device has the characteristics of large borax grains and no caking of products.

Description

Technical Field

[0001] The utility model belongs to the technical field of efficient comprehensive utilization of salt lake resources, and specifically discloses a crystallization system for preparing borax from salt lake brine. Background Art

[0002] According to the characteristics of crystallization kinetics, crystal kinetics optimizes crystal size and shape by controlling supersaturation. Regarding crystal nucleation and growth, there is a certain relationship between the crystallization process and the degree of supersaturation of the solution. Controlling the crystallization process is to control the supersaturation, because the entire crystallization process occurs in the metastable zone. If the supersaturation is low, the nucleation rate is slow, the number of crystals is small and the growth rate is slow, so the crystal particles will grow; if the supersaturation is high, the nucleation rate is fast, explosive nucleation is likely to occur, so the crystal particles will be smaller.

[0003] When the borax mother liquor just starts to crystallize, the surface area of ​​the crystals in the solution is small, and the nucleation rate is higher than the growth rate. If you want to increase the particle size of borax, the larger the particle size, the larger the surface area, the borax growth rate needs to be greater than the nucleation rate. The borax preparation process using salt lake brine as raw material is rapidly cooled in the crystallization tower, which cannot provide enough surface area for crystal growth in time. The supersaturation will accumulate and increase at the beginning of cooling, forming a higher supersaturation, and the nucleation rate will dominate. The crystal nucleation rate is faster than the growth rate, and powdered borax with smaller particle size will precipitate. Powdered borax does not affect the intrinsic product quality, but the characteristic of containing water of crystallization makes borax have agglomeration characteristics. The large specific surface area of ​​powdered crystals leads to a greatly increased contact area between crystals, which makes the powdered borax product easy to agglomerate, which is not conducive to the production and use of downstream customers. Utility Model Content

[0004] The utility model aims to provide a crystallization system for preparing borax from salt lake brine, so as to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above-mentioned purpose, the utility model provides the following technical scheme: a crystallization system for preparing borax from salt lake brine, a crystallization system for preparing borax from salt lake brine, the crystallization system comprising a first hot-melt batching trough, a second hot-melt batching trough, a first set of crystallization tanks, a second set of crystallization tanks, a buffer tank, and a centrifuge; the first set of crystallization tanks comprises a first crystallization tank, a second crystallization tank, a third crystallization tank, and a fourth crystallization tank, the second set of crystallization tanks comprises a fifth crystallization tank, a sixth crystallization tank, a seventh crystallization tank, and an eighth crystallization tank, the first hot-melt batching trough collects borax mother liquor, mixes it with a surfactant additive, and then enters the first set of crystallization tanks in sequence, the first set of crystallization tanks are cooled to a certain temperature and then enter the second hot-melt batching trough in a discharge and introduction groove manner, the materials in the second hot-melt batching trough are pumped to the second set of crystallization tanks in sequence through a pump, continue to cool to a certain temperature and enter the buffer tank and then enter the centrifuge for separation.

[0006] Furthermore, the crystallization tank is equipped with a temperature sensor, a liquid level display and alarm, and electric regulating valves for the inlet and outlet pipelines, and the regulating valves can be interlocked according to the set temperature and liquid level to achieve full automatic control.

[0007] Furthermore, the volume of the crystallization tank is 8m 3 It is equipped with cooling coils and stirring devices, which can strictly control the cooling rate and insulation time by controlling the cooling water flow rate. The cooling water is cooled by a cooling tower and can be recycled.

[0008] Furthermore, the crystallization tank and supporting pipelines are made of fiberglass to prevent pipeline corrosion and crystal scaling on the inner wall. The first set of crystallization tanks and the second set of crystallization tanks are both 4 in number, and the centrifuge is a four-legged flat-plate scraper unloading centrifuge.

[0009] Compared with the prior art, the utility model has the following beneficial effects: the utility model provides a crystallization system for preparing borax from salt lake brine, wherein the borax mother liquor enters the first hot-melt batching tank and then enters two sets of crystallization tanks for two-stage cooling, and the material enters a plurality of crystallization tanks through an automatic material inlet and outlet control system for stable cooling to allow borax nuclei to be generated and crystals to fully grow, thereby realizing continuous borax preparation, and the crystallization system has a short process flow and low energy consumption, and can effectively increase the particle size of borax without causing agglomeration. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a schematic diagram of the structure of the preferred crystallization system of the present invention.

[0011] Figure numerals: 1, first hot melt batching tank; 2, second hot melt batching tank, 3, first crystallization tank; 4, second crystallization tank; 5, third crystallization tank; 6, fourth crystallization tank; 7, fifth crystallization tank; 8, sixth crystallization tank; 9, seventh crystallization tank; 10, eighth crystallization tank; 11, buffer tank; 12, centrifuge; 13, pump. DETAILED DESCRIPTION

[0012] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0013] See also Figure 1 , the utility model provides the embodiment:

[0014] Example 1

[0015] The utility model provides a technical solution: the crystallization system comprises a first hot melt batching tank 1, a second hot melt batching tank 2, a first crystallization tank 3, a second crystallization tank 4, a third crystallization tank 5, a fourth crystallization tank 6, a fifth crystallization tank 7, a sixth crystallization tank 8, a seventh crystallization tank 9, an eighth crystallization tank 10, a buffer tank 11, a centrifuge 12, and a pump 13; the first set of crystallization tanks comprises the first crystallization tank 3, the second crystallization tank 4, the third crystallization tank 5, and the fourth crystallization tank 6; the second set of crystallization tanks comprises the fifth crystallization tank 7, the sixth crystallization tank 8, the seventh crystallization tank 9, and the eighth crystallization tank 10.

[0016] The first hot melt batching tank 1 and the second hot melt batching tank 2 are of the same size and specifications, and are both equipped with a stirring device and a thermometer. The borax mother liquor flow rate is 23m 3 / h or so and enter the first hot melt batching tank 1 at a temperature of about 75°C. The borax mother liquor and additives are mixed under stirring, and the temperature change is monitored in real time. If there is a large deviation in the flow rate and temperature, the upstream process parameters can be immediately fed back and corrected.

[0017] The first hot melt batching tank 1 is connected to the first set of crystallization tanks 3, 4, 5, 6 by a group of pumps 13 and pipelines, and the discharge of the first set of crystallization tanks 3, 4, 5, 6 is introduced into the second hot melt batching tank 2 by a ground groove.

[0018] The crystallization tank and its supporting pipelines are made of fiberglass to prevent pipeline corrosion and crystal scaling on the inner wall.

[0019] The size of the first and second sets of crystallization tanks are both 8m 3 The interior is equipped with temperature sensors, liquid level displays and alarms, and the inlet and outlet pipelines are equipped with electric valves. All electrical devices are connected to the central control. The borax mother liquor with a temperature of about 75°C is pumped to the crystallization tanks 3, 4, 5, and 6 at a speed of 25m 3 / h flow rate feeding, after the first crystallizer 3 liquid level reaches the set value, the liquid level alarm is automatically issued, the inlet valve is automatically closed, the system starts timing, and then the second crystallizer 4 inlet valve is automatically opened, and the other crystallizers are fed in sequence according to this method.

[0020] In this embodiment, the first stage of cooling begins when the inlet valve is closed and the cooling time is 1 hour. The temperature drops from 75°C to 60°C within 1 hour. The cooling water flow rate in the coil is adjusted appropriately according to the temperature and time changes to achieve a smooth cooling. When the temperature drops to 60°C, the valves at the bottom of the crystallizer open automatically one by one, and the water flows into the ditch and is transferred to the second hot melt batching tank 2. The outlet valve is automatically closed after the low liquid level alarm, and the system automatically defaults to the next feeding device.

[0021] The purpose of introducing the borax mother liquor into the second hot melt batching tank 2 by trench introduction after cooling to 60°C is, firstly, to reduce the use of equipment and pipelines and reduce production costs; secondly, the crystallization of the borax mother liquor after a period of cooling can be visually observed, and the crystallization effect can be judged to facilitate timely correction of process parameters.

[0022] The cooling water is combined into a pipe network, and each crystallizer is equipped with a cooling water pump and a flow regulating valve. The heated cooling water goes to the cooling tower for natural cooling before entering the pipe network, thus realizing the recycling of cooling water.

[0023] The second hot melt batching tank 2 is connected to the second set of crystallization tanks 7, 8, 9, 10 by a group of pumps 13 and pipelines. The second set of crystallization tanks 7, 8, 9, 10 are connected to the buffer tank 11 by pumps 13 respectively, and the outlet of the buffer tank 11 is connected to the inlet of the centrifuge 12.

[0024] In this embodiment, the material temperature in the second hot melt batching tank 2 is about 60°C, and the borax mother liquor is pumped to the crystallization tanks 7, 8, 9, and 10 at a speed of 25m / s. 3 / h flow rate feed, the fifth crystallizer 7 liquid level reaches the set value, automatically sends out the liquid level alarm, the inlet valve automatically closes, the system starts timing, and then automatically opens the sixth crystallizer 8 inlet valve, according to this method to complete the feeding in sequence, the second stage of cooling.

[0025] In the second stage of cooling, the material temperature is reduced from 60°C to 50°C. After cooling for 1 hour, the valve at the bottom of the crystallizer automatically opens and the crystallizer is pumped at 25m 3 / h flow rate to pump the borax mother liquor solid-liquid mixture into the buffer tank 11, the low liquid level alarm automatically closes the outlet electric valve and pump, and the system automatically defaults to the next feeding device.

[0026] The buffer tank 11 is at a high position, and the centrifuge 12 is at a low position. The buffer tank is equipped with a stirring device to fully mix the solid and liquid of the borax mother liquor. According to the high and low position difference, the materials enter two four-legged flat-plate scraper unloading centrifuges, and borax is obtained after centrifugation. The products used in this patent, centrifuge, pump, temperature sensor, alarm, and liquid level display are all existing products on the market, and there is no need to describe the working principle in detail before introducing the functions.

[0027] The principle of the utility model is the crystallization kinetics theory. Crystal kinetics optimizes the crystal size and shape by controlling the supersaturation of the solution. Regarding crystal nucleation and growth, there is a certain relationship between the crystallization process and the supersaturation of the solution. Controlling the crystallization process is to control the supersaturation, because the entire crystallization process occurs in the metastable zone. If the supersaturation is low, the nucleation rate is slow, the number of crystals is small and the growth rate is slow, so the crystal particles will grow; if the supersaturation is high, the nucleation rate is fast, and explosive nucleation is likely to occur, so the crystal particles will be smaller. The use of a multi-stage cooling method can prevent the crystallization temperature from dropping rapidly and linearly, causing the borax crystals to grow untimely, thereby causing a large amount of powdered borax crystals to precipitate. The utility model adopts two-stage cooling, the purpose of which is to allow the borax crystals to fully grow at this temperature. The first set of crystallization tank cooling is the process of generating crystal nuclei in the borax solution, and the second set of crystallization tank cooling is the process of crystal nuclei growing in the borax solution.

[0028] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention. Any reference numeral in a claim should not be regarded as limiting the claim to which it relates.

Claims

1. A crystallization system for preparing borax from salt lake brine, characterized in that: include: The crystallization system comprises a first hot melt batching tank, a second hot melt batching tank, a first set of crystallization tanks, a second set of crystallization tanks, a buffer tank, and a centrifuge; The first set of crystallization tanks includes a first crystallization tank, a second crystallization tank, a third crystallization tank, and a fourth crystallization tank, and the second set of crystallization tanks includes a fifth crystallization tank, a sixth crystallization tank, a seventh crystallization tank, and an eighth crystallization tank. The first hot-melt batching tank collects borax mother liquor, which is mixed with a surfactant additive and then enters the first set of crystallization tanks in sequence. After the first set of crystallization tanks are cooled to a certain temperature, they are discharged and introduced into the second hot-melt batching tank in a ground groove manner. The materials in the second hot-melt batching tank are pumped to the second set of crystallization tanks in sequence, and continue to be cooled to a certain temperature to enter the buffer tank and then enter the centrifuge for separation.

2. The crystallization system for preparing borax from salt lake brine according to claim 1, characterized in that: The first set of crystallization tanks and the second set of crystallization tanks are equipped with temperature sensors, liquid level displays and alarms, and electric regulating valves for inlet and outlet pipelines, and the regulating valves can be interlocked according to the set temperature and liquid level.

3. The crystallization system for preparing borax from salt lake brine according to claim 1, characterized in that: The volume of the first set of crystallization tanks and the second set of crystallization tanks is 8m 3 It is also equipped with cooling coils and stirring devices, which can strictly control the cooling rate and insulation time by controlling the cooling water flow rate. The cooling water is cooled by a cooling tower.

4. The crystallization system for preparing borax from salt lake brine according to claim 1, characterized in that: The supporting pipes of the first set of crystallization tanks and the second set of crystallization tanks are both made of fiberglass, there are four of each of the first set of crystallization tanks and the second set of crystallization tanks, and the centrifuge is a four-legged flat-plate scraper unloading centrifuge.

Images