Production process for centrifugal granulation of calcium chloride

Abstract

The invention discloses a calcium chloride centrifugal granulation production process and belongs to the technical field of centrifugal granulation. The process comprises the following steps: dissolving raw materials, and adding the raw materials to dissolve and prepare an aqueous solution; purification and impurity removal: adding an impurity removal agent, and filtering twice; carrying out deep concentration, preheating liquid calcium chloride, carrying out gas-liquid separation, and then heating and separating again; centrifugally granulating, and drying and granulating the concentrated solution by a granulator; the method solves the problems of difficult dissolution, complex process, poor cleanliness, poor fluidity, easy moisture absorption and caking and limited form adaptability of spherical, sheet and powdery calcium chloride products in the production process and application in the prior art, and is mainly applied to centrifugal granulation of calcium chloride.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of centrifugal granulation, in particular to a production process of calcium chloride centrifugal granulation. BACKGROUND

[0002] The existing calcium chloride products are mainly divided into three types: spherical, flaky and powdery, each of which has its own focus in production process, and also has different technical limitations.

[0003] The core production process of spherical calcium chloride is raw material dissolution→purification and impurity removal→concentration and crystallization→granulation and molding→drying and screening. During production, the calcium chloride raw material is first put into a dissolution tank and dissolved by heating and stirring with 50-80℃ steam. The solid raw material needs to be adjusted to a 30-40% aqueous solution, and the liquid raw material can be directly filtered. Then, impurities such as iron and magnesium ions are removed by adding sodium carbonate, sodium hydroxide and other impurity removal agents, and a pure solution is obtained by precipitation and filtration. The pure solution is then concentrated to 50-60% by a multi-effect evaporator under negative pressure, and then sent to a crystallizer for cooling and crystallization to form a crystal slurry. The core step of spherical granulation is to spray a small amount of water or dilute solution into the calcium chloride powder or fine crystals in the roller, and rely on rolling to agglomerate into spheres. Finally, the product is dried by hot air at 120-180℃ to a moisture content of ≤1%, and then screened by a multi-layer screen to obtain finished products of different particle sizes such as 2-5mm and 5-8mm. However, this product has the disadvantages of not easy to dissolve during use, complex process and poor product cleanliness.

[0004] The core process of flaky calcium chloride is "raw material dissolution→purification and impurity removal→concentration→thin film evaporation to make flakes→cooling and drying". The core advantage is to realize continuous flaking by thin film evaporation. The production steps are as follows: the calcium chloride raw material is dissolved by heating at 60-80℃, and adjusted to a 35-45% aqueous solution and filtered to remove impurities. After adding impurity removal agents to precipitate heavy metal ions, a pure solution is obtained by plate and frame filtration or precision filtration. Then, the solution is concentrated to 60-70% by a single-effect or double-effect evaporator under normal pressure or slightly negative pressure, reducing the difficulty of flaking. In the core step of thin film evaporation flaking, the concentrated solution is pumped into a roller scraper evaporator to form a uniform liquid film on the inner wall of the roller. After evaporation of water by steam heating, the flakes are scraped off by the scraper to form flaky flakes. Finally, the flaky product is cooled to room temperature, and then screened by a vibrating screen to remove broken ends and large blocks to obtain finished products with a thickness of 0.5-2mm. The disadvantages of this product are quite prominent. Not only is it not easy to dissolve during use, but also has poor flowability, resulting in low manual feeding efficiency. The flaky edges contain surface water, which is easy to absorb moisture and stick together, requiring high storage and moisture-proof packaging. At the same time, the regularity of the shape is insufficient, and the adaptability in precision chemical industry and other scenes is limited. The process flow is relatively complex, the product cleanliness is poor, and the sharp edges are easy to damage the packaging.

[0005] The production of powdery calcium chloride is carried out around "raw material dissolution → impurity removal → deep concentration → drying / pulverization powdering → screening purification", and the core is to realize powdering through atomization or pulverization. When producing, first, the calcium chloride raw material is dissolved into a 30-40% aqueous solution at 50-70°C, and mechanical impurities are removed by filtration; after adding impurity removal agent to precipitate impurity ions, pure filtrate is obtained by filtration; then, through three-effect evaporator negative pressure concentration to 60-70%, to reduce the drying energy consumption and avoid caking; powdering forming is the core step, which is divided into two mainstream processes: spray drying powdering: the concentrated solution is high-pressure atomized and contacted with hot air at 180-220°C, and the water is evaporated into powder in an instant, and pulverization: the solution is cooled and crystallized, centrifuged, and then pulverized into powder by a pulverizer; finally, the coarse particles and impurities are removed by a vibrating screen, and if necessary, secondary drying is performed to control the moisture content.

[0006] The disadvantages of the product vary slightly due to the powdering process. The spray-dried powder has fine particle size, is extremely easy to absorb moisture and caking, has high requirements for transportation and storage, and has poor flowability, easy wall hanging, and easy dusting affecting the on-site environment. The pulverized powdery product has the problems of uneven particle size, irregular shape, poor flowability, easy moisture absorption, and poor mixing application. SUMMARY

[0007] In order to solve the problems of not easy to dissolve, complex process, poor cleanliness, poor flowability, easy to absorb moisture and caking, and limited form adaptability of the spherical, flaky and powdery calcium chloride products in the production process and application in the background art.

[0008] A centrifugal granulation production process of calcium chloride, characterized in that it comprises the following processes:

[0009] Step one: raw material dissolution, the raw material is dissolved into an aqueous solution;

[0010] Step two: impurity removal, impurity removal agent is added, and filtration is performed twice;

[0011] Step three: deep concentration, the liquid calcium chloride is preheated, gas-liquid separation is performed, then it is heated again, and then separated again;

[0012] Step four: centrifugal granulation, the concentrated solution is dried and granulated by a granulator;

[0013] Step five: screening and packaging, coarse particles are removed by screening, and the finished product is packaged.

[0014] Specifically:

[0015] Step one: raw material dissolution and pretreatment

[0016] The solid calcium chloride is put into a dissolution tank, heated to 50-70°C and stirred to dissolve, and adjusted to a 30-40% aqueous solution, which is transferred to a raw material storage tank by a pump for storage and precipitation;

[0017] Step two: purification and impurity removal

[0018] Impurities are removed by adding an impurity removal agent to the aqueous solution of step one to precipitate iron and magnesium impurity ions. After standing, the solution is filtered through a 200-mesh plate frame and stored. The solution is then filtered through two precision filters with pore sizes of 0.2 μm and 0.4 μm to obtain a pure calcium chloride solution.

[0019] Step three: deep concentration

[0020] The liquid calcium chloride of step two is preheated to 50-100°C in a preheater and then fed into a two-effect evaporator. The heated solution is then fed into a two-effect separator for vapor-liquid separation. The temperature of the liquid leaving the two-effect separator is 70-110°C, the vapor temperature is controlled at 80-125°C, and the vacuum degree of the two-effect separator is controlled at -0.05-0.09 MPa. The separated liquid is then fed into a one-effect evaporator, heated, and then fed into a one-effect separator for further vapor-liquid separation. The temperature of the liquid leaving the one-effect separator is 120-140°C, the vapor temperature is controlled at 140-170°C, and the vacuum degree of the one-effect separator is controlled at -0.05-0.09 MPa. The liquid calcium chloride is obtained by vapor-liquid separation in the one-effect separator.

[0021] Step four: granulation and molding

[0022] The concentrated solution of step three is fed into a granulator, which granulates the concentrated solution and feeds it into a drying tower. The hot air in the drying tower rapidly evaporates the water on the surface of the product, leaving the water in the middle of the product. The product is then collected and transported to obtain the finished product.

[0023] Step five: screening and packaging

[0024] The centrifugally granulated product is screened by a vibrating screen to remove coarse granules, and then packaged by a packaging machine.

[0025] Further, the impurity removal agent is sodium hydroxide or sodium carbonate.

[0026] The present application has the following advantages:

[0027] The process design of the present application is advanced, highly operable, controllable in process parameters, and can realize industrial production.

[0028] The entire process from the entry of the product liquid into the evaporator to the packaging of the finished product is fully sealed, clean and reliable, and meets the requirements of food and pharmaceutical grades.

[0029] The method of the present application produces crystals with high purity, which can meet the requirements of superior products; the dissolution is fast, and the product can be used while being dissolved; after dissolution, the product is clear and transparent without impurities; the automatic assembly line is adopted to reduce external pollution, the bulk density of the produced crystals is small, the transportation space is saved, and the product is not easy to deliquesce; the product is 50-150 mesh flow centrifugal granulation, which can be directly mixed with other products in solid form. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 D50, 218 μm, 69 mesh particle size diagram of the centrifugal granulated calcium chloride of the present application;

[0031] Figure 2 D50, 93 μm, 160 mesh particle size diagram of the centrifugal granulated calcium chloride of the present application;

[0032] Figure 3 D50, 122 μm, 123 mesh particle size diagram of the centrifugal granulated calcium chloride of the present application;

[0033] Figure 4 Process flow diagram of the present application. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0035] The process of the centrifugal granulated calcium chloride is as follows:

[0036] Step one: raw material dissolution and pretreatment:

[0037] Solid calcium chloride is put into a dissolution tank and dissolved by heating to 50-70°C with stirring, and a 30-40% aqueous solution is prepared and pumped into a raw material storage tank for storage and precipitation;

[0038] Step two: purification and impurity removal:

[0039] Impurity removal agent is added to the aqueous solution of step one to precipitate iron and magnesium impurity ions, and after standing, the solution is filtered through a 200 mesh plate frame and stored, and then filtered through 0.2 μm and 0.4 μm precision filters to obtain pure calcium chloride clear solution;

[0040] Step three: deep concentration:

[0041] The liquid calcium chloride of step two is put into a preheater to be preheated to 50-100℃, then enters a two-effect evaporator to be heated and then enters a two-effect separator to be vapor-liquid separated, the liquid temperature of the two-effect separator is 70-110℃, the steam temperature is controlled at 80-125℃, the vacuum degree of the two-effect separator is controlled at -0.05--0.09MPa, the liquid after the vapor-liquid separation enters a one-effect evaporator to be heated and then enters a one-effect separator to be vapor-liquid separated again, the liquid temperature of the one-effect separator is 120-140℃, the steam temperature of the one-effect separator is controlled at 140-170℃, the vacuum degree of the one-effect separator is controlled at -0.05--0.09MPa, and the liquid calcium chloride is obtained through the vapor-liquid separation of the one-effect separator.

[0042] Step four: granulation forming:

[0043] The concentrated liquid is transported to a granulator, the granulator granulates the concentrated liquid into a drying tower, the concentrated liquid is contacted with hot air at 200-400℃, the surface moisture of the centrifugal granulation is removed in the granulation room, the intermediate moisture of the centrifugal granulation is retained, and the finished product is obtained after collection and transportation;

[0044] Step five: screening and packaging:

[0045] The centrifugal granulation is screened by a vibrating screen to remove coarse centrifugal granulation, and the product is packaged by a packaging machine.

[0046] Example 1

[0047] A production process of calcium chloride centrifugal granulation, the steps are as follows:

[0048] Step one: raw material dissolution and pretreatment:

[0049] Solid calcium chloride is put into a dissolving tank, heated to 50-70℃ and stirred to dissolve, and a 30-40% aqueous solution is prepared, which is transferred to a raw material storage tank by a pump for storage and precipitation;

[0050] Step two: purification and impurity removal:

[0051] Impurity removal agent is added to the aqueous solution of step one to precipitate iron and magnesium impurity ions, after standing, it is filtered through a 200-mesh plate frame and stored, and then filtered through two precision filters of 0.2μm and 0.4μm to obtain a pure calcium chloride clear liquid;

[0052] Step three: deep concentration:

[0053] The liquid calcium chloride of step two is preheated to 50°C in a preheater, then sprayed into a two-effect evaporator for heating, and then sprayed into a two-effect separator for vapor-liquid separation. The liquid temperature at the outlet of the two-effect separator is 70°C, the vapor temperature is controlled at 80°C, and the vacuum degree of the two-effect separator is controlled at -0.05 MPa. The separated liquid is sprayed into a one-effect evaporator for heating, and then sprayed into a one-effect separator for vapor-liquid separation. The liquid temperature at the outlet of the one-effect separator is 130°C, the vapor temperature is controlled at 140°C, and the vacuum degree of the one-effect separator is controlled at -0.05 MPa. The liquid calcium chloride is obtained through vapor-liquid separation of the one-effect separator;

[0054] Step four: granulation and molding

[0055] The liquid calcium chloride of step three is transported to a dust-free granulation chamber through a pipeline. The temperature of the granulation chamber is 250°C. The pipeline is controlled at a temperature of 130°C when transporting the liquid calcium chloride. The granulation is performed by a granulator. The granulated calcium chloride powder with a particle size of 69 mesh is obtained.

[0056] Example 2

[0057] A production process of calcium chloride powder, the steps of which are as follows:

[0058] Step one: raw material dissolution and pretreatment

[0059] Solid calcium chloride is added to a dissolution tank and dissolved by heating to 50-70°C with stirring to prepare a 30-40% aqueous solution. The aqueous solution is pumped into a raw material storage tank for storage and precipitation.

[0060] Step two: purification and impurity removal

[0061] Impurity removal agents are added to the aqueous solution of step one to precipitate iron and magnesium impurity ions. After standing, the solution is filtered through a 200-mesh plate frame and then filtered through two precision filters with pore sizes of 0.2 μm and 0.4 μm to obtain a pure calcium chloride clear solution.

[0062] Step three: deep concentration

[0063] The liquid calcium chloride of step two is preheated to 100°C in a preheater, then sprayed into a two-effect evaporator for heating, and then sprayed into a two-effect separator for vapor-liquid separation. The liquid temperature at the outlet of the two-effect separator is 110°C, the vapor temperature is controlled at 125°C, and the vacuum degree of the two-effect separator is controlled at 0.09 MPa. The separated liquid is sprayed into a one-effect evaporator for heating, and then sprayed into a one-effect separator for vapor-liquid separation. The liquid temperature at the outlet of the one-effect separator is 140°C, the vapor temperature is controlled at 170°C, and the vacuum degree of the one-effect separator is controlled at 0.09 MPa. The liquid calcium chloride is obtained through vapor-liquid separation of the one-effect separator;

[0064] Step four: granulation and molding

[0065] The liquid calcium chloride of step three is transported through a pipeline to a dust-free granulation chamber, the temperature of the granulation chamber is 350 DEG C, the granulation is carried out by a granulator, the temperature of the pipeline is controlled at 160 DEG C when the liquid calcium chloride is transported, and the calcium chloride powder with a crystal size of 160 meshes is prepared.

[0066] Example 3

[0067] A production process of calcium chloride powder, the steps are as follows:

[0068] Step one: raw material dissolution and pretreatment:

[0069] The solid calcium chloride is put into a dissolving tank, heated to 50-70 DEG C, stirred and dissolved, and adjusted to a 30-40% aqueous solution, which is pumped into a raw material storage tank for storage and precipitation;

[0070] Step two: purification and impurity removal:

[0071] Impurity removal agent is added to the aqueous solution of step one to precipitate iron and magnesium impurity ions, and after standing, it is stored by filtering through a 200 mesh plate frame, and then filtered through two precision filters of 0.2 μm and 0.4 μm to obtain a pure calcium chloride clear solution;

[0072] Step three: deep concentration:

[0073] The liquid calcium chloride of step two is preheated to 75 DEG C in a preheater, then sprayed into a two-effect evaporator for heating, and then sprayed into a two-effect separator for vapor-liquid separation, the liquid temperature of the two-effect separator is 90 DEG C, the steam temperature is controlled at 100 DEG C, the vacuum degree of the two-effect separator is controlled at -0.07 Mpa, the separated liquid is sprayed into a one-effect evaporator for heating, and then sprayed into a one-effect separator for vapor-liquid separation again, the liquid temperature of the one-effect separator is 135 DEG C, the steam temperature of the one-effect separator is controlled at 155 DEG C, and the vacuum degree of the one-effect separator is controlled at -0.07 Mpa, and the liquid calcium chloride is obtained by vapor-liquid separation through the one-effect separator;

[0074] Step four: granulation and molding

[0075] The liquid calcium chloride of step three is transported through a pipeline to a dust-free granulation chamber, the temperature of the granulation chamber is 300 DEG C, the granulation is carried out by a granulator, the temperature of the pipeline is controlled at 150 DEG C when the liquid calcium chloride is transported, and the calcium chloride powder with a crystal size of 123 meshes is prepared.

[0076] The present application is simple to operate, convenient to use, and suitable for comprehensive promotion and application. Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and variations can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A production process for calcium chloride by centrifugal granulation, characterized in that, Including the following processes: Step 1: Dissolve the raw materials and add them to the prepared aqueous solution. Step 2: Purification and impurity removal: Add impurity removal agent and filter twice; Step 3: Deep concentration, preheat liquid calcium chloride, perform gas-liquid separation, then heat again, and separate again; Step 4: Centrifugal granulation, the granulator dries and granulates the concentrate; Step 5: Screening and packaging. Screening removes coarse particles, and packaging is done on the finished product.

2. The production process of calcium chloride centrifugal granulation according to claim 1, characterized in that, Step 1: Dissolving the raw materials Solid calcium chloride is added to a dissolving tank, heated to 50-70℃ and stirred to dissolve, and then prepared into a 30-40% aqueous solution, which is then pumped into a raw material storage tank for storage and precipitation. Step 2: Purification and Impurity Removal Add a purifying agent to the aqueous solution from step one to precipitate iron and magnesium impurity ions. After standing, filter through a 200-mesh plate and frame filter and store. Then filter through two precision filters of 0.2μm and 0.4μm to obtain a pure calcium chloride solution. Step 3: Deep Concentration The liquid calcium chloride from step two is preheated to 50-100℃ in a preheater, then heated in a second-effect evaporator before entering a second-effect separator for vapor-liquid separation. The liquid outlet temperature of the second-effect separator is 70-110℃, the steam temperature is controlled at 80-125℃, and the vacuum degree of the second-effect separator is controlled at -0.05-0.09MPa. The separated liquid is then heated in a first-effect evaporator and then enters a first-effect separator for further vapor-liquid separation. The liquid outlet temperature of the first-effect separator is 120-140℃, the steam temperature is controlled at 140-170℃, and the vacuum degree of the first-effect separator is controlled at -0.05-0.09MPa. Liquid calcium chloride is obtained through vapor-liquid separation in the first-effect separator. Step 4: Granulation and Molding The liquid calcium chloride from step three is transported through a pipeline to a dust-free granulation chamber at a temperature of 200-300°C. Granulation is performed using a granulator. The temperature of the pipeline is controlled at 120-150°C while transporting the liquid calcium chloride, resulting in calcium chloride dihydrate powder with a crystallization particle size of 70-100 mesh. Step 5: Sieving and Packaging Centrifugal granulation is followed by screening with a vibrating screen to remove coarse granules, and then the product is packaged by a packaging machine.

3. The production process of calcium chloride centrifugal granulation according to claim 2, characterized in that, The impurity remover is sodium hydroxide or sodium carbonate.

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