Device for preparing calcium chloride from mannheim potassium sulfate byproduct low-quality hydrochloric acid

Abstract

The utility model relates to the field of chemical engineering and environmental protection, and particularly provides a device for preparing calcium chloride by using low-quality hydrochloric acid as a mannheim potassium sulfate byproduct, which comprises at least one stage of reaction tank, a neutralizing tank, a clarifying tank and filtering equipment which are connected in sequence, filtrate of the filtering equipment is conveyed to a flash tower, and a discharge pipeline at the lower part of the flash tower is connected to granulation drying equipment; the reaction tank is provided with a mannheim potassium sulfate byproduct low-quality hydrochloric acid adding port, a calcium carbonate feeding port is further formed in the reaction tank, and the neutralizing tank is provided with a calcium hydroxide adding port. The device uses potassium sulfate byproduct low-quality hydrochloric acid as a raw material to prepare anhydrous chloride, is simple in process flow, high in hydrochloric acid consumption and high in product yield, and solves the problem that potassium sulfate byproduct hydrochloric acid is not treated.

Description

Technical Field

[0001] The utility model belongs to the technical field of chemical industry and environmental protection, and relates to a device for preparing calcium chloride by producing low-quality hydrochloric acid as a by-product of Mannheim potassium sulfate. Background Art

[0002] Potassium sulfate production in my country primarily utilizes the Mannheim process, which involves reacting concentrated sulfuric acid with potassium chloride to produce solid potassium sulfate. This process produces a large amount of hydrochloric acid as a by-product. This industrial by-product, hydrochloric acid, is a hazardous chemical that is difficult to store and transport and has low economic value. The difficulty of handling this by-product often limits the capacity of production facilities, making the consumption and disposal of excess hydrochloric acid a major issue that needs to be addressed.

[0003] Calcium chloride, an inorganic salt composed of chlorine and calcium, is highly hygroscopic and easily deliquesces in air, requiring airtight storage. Calcium chloride generates heat when in contact with water, has strong water absorption, and a low freezing point. It is commonly used as a de-icing agent, desiccant, coagulant, stabilizer, and other applications. It performs well in areas such as port fog removal, road dust collection, and textile fire prevention, and holds significant application value. Currently, domestic calcium chloride production processes fall into two main categories. One utilizes an alkali-based calcium solution (referred to as "alkali-based calcium production"). The most common methods include beach sun-drying concentration, heating evaporation concentration, and underground circulation. This process primarily involves washing the raw materials with the alkali solution, re-drying, evaporation, concentration, and calcium block production, resulting in relatively high costs. The other utilizes hydrochloric acid to dissolve calcium carbonate (referred to as "acid-based calcium production"). Limestone and hydrochloric acid are added to a reaction tank in appropriate proportions to produce a calcium solution. The pH is adjusted to remove impurities, and the solution is then concentrated and dried to produce calcium chloride in powder, block, granular, or spherical forms. Among them, the acid method of calcium chloride process is relatively simple, and the amount of hydrochloric acid used is large, which is an effective means of disposing of the hydrochloric acid by-product of potassium sulfate.

[0004] Hubei Sanning Chemical uses the Mannheim process to produce potassium sulfate, producing a large amount of low-quality hydrochloric acid as a byproduct. This hydrochloric acid, which contains high levels of sulfate and other impurities, is difficult to handle and transport, and its export price averages 280 yuan per ton, making it virtually worthless. To address this issue, we propose a Mannheim potassium sulfate byproduct calcium chloride production plant, which uses this low-quality hydrochloric acid while improving economic efficiency. Summary of the Invention

[0005] The utility model provides a device for preparing calcium chloride from low-quality hydrochloric acid produced as a by-product of potassium sulfate in Mannheim. The device uses the low-quality hydrochloric acid produced as a by-product of potassium sulfate as a raw material to prepare anhydrous chlorination. The device has a simple process flow, a large hydrochloric acid consumption, and a high product yield, thus solving the problem of having no place to dispose of the hydrochloric acid produced as a by-product of potassium sulfate.

[0006] The technical solution of the utility model is to provide a calcium chloride preparation device with Mannheim potassium sulfate as a by-product and low-quality hydrochloric acid. The device comprises at least one primary reaction tank, a neutralization tank, a clarification tank and a filtering device connected in sequence. The filtrate of the filtering device is transported to a flash tower, and a discharge pipe at the lower part of the flash tower is connected to a granulation and drying device. The reaction tank is provided with an inlet for adding the Mannheim potassium sulfate as a by-product and low-quality hydrochloric acid. The reaction tank is also provided with a calcium carbonate feeding port. The neutralization tank is provided with an inlet for adding calcium hydroxide.

[0007] In an alternative solution, the reactor is configured as a two-stage reactor. The primary reactor is equipped with a hydrochloric acid inlet and a calcium carbonate inlet. Its overflow port is connected to the secondary reactor via a pipeline. The secondary reactor is also equipped with a calcium carbonate inlet. The discharge port of the secondary reactor is connected to the neutralization tank. This ensures that the hydrochloric acid can react fully, improves the utilization rate of raw materials, and is economical and environmentally friendly.

[0008] In an optional solution, the filtering equipment is a plate and frame filter press, and the filter residue treated by the filter press is discharged.

[0009] In an optional solution, a filtrate buffer tank is further provided between the filtration equipment and the flash tower.

[0010] In an optional solution, the reaction tank, neutralization tank, clarification tank and filtrate buffer tank are all closed containers.

[0011] In an optional solution, a heat exchanger is further provided outside the flash tower, and a discharge pipe connected to the granulation drying equipment is further provided with a branch pipe, which is connected to the return port of the flash tower after passing through the heat exchanger to form a circulation loop.

[0012] In an optional solution, a stirrer is provided in the reaction tank and the neutralization tank, and the driving motor of the stirrer is an explosion-proof motor.

[0013] In an optional solution, the granulation and drying equipment is a granulation and drying fluidized bed.

[0014] The utility model has the following beneficial effects:

[0015] This device uses low-quality hydrochloric acid, a byproduct of potassium sulfate, as raw material. It utilizes the reaction between calcium carbonate and hydrochloric acid to produce an acid solution high in calcium chloride. Calcium hydroxide emulsion is then added to the acid solution to adjust the pH, causing impurities such as iron and magnesium to form hydroxide precipitates. This solution is then filtered to remove these impurities, resulting in a relatively pure calcium chloride solution. This solution is then evaporated, concentrated, and dried at high temperature to produce anhydrous calcium chloride. This process is simple, consumes a large amount of hydrochloric acid, and produces a high product yield, solving the problem of having no place to dispose of the hydrochloric acid produced as a byproduct of potassium sulfate.

[0016] The CaCl2 content in the anhydrous calcium chloride prepared using this device can reach more than 94%, meeting the national qualified product standards. It can be used in snow melting agents, desiccants, coagulants, stabilizers, etc., expanding the market for anhydrous calcium chloride. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the structure of the present invention. In the figure, 1 is a hydrochloric acid delivery pump, 2 is a primary reaction tank, 3 is a secondary reaction tank, 4 is a neutralization tank, 5 is a calcium hydroxide emulsion delivery pump, 6 is a neutralization tank discharge pump, 7 is a clarification tank, 8 is a clarification tank discharge pump, 9 is a filtration device, 10 is a filtrate buffer tank, 11 is a filtrate delivery pump, 12 is a flash tower, 13 is a flash tower discharge pump, 14 is a heat exchanger, and 15 is a granulation and drying device. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments and appended Figure 1 The embodiments of the present invention are described in detail, but those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention.

[0019] like Figure 1 As shown, the utility model provides a device for producing calcium chloride from low-quality hydrochloric acid produced as a by-product of Mannheim potassium sulfate, comprising at least one primary reaction tank, a neutralization tank 4, a clarification tank 7 and a filtering device connected in sequence, wherein the filtrate of the filtering device is transported to a flash tower 12, and a discharge pipe at the lower part of the flash tower is connected to a granulation and drying device 15; the reaction tank is provided with a Mannheim potassium sulfate by-product low-quality hydrochloric acid inlet, through which the hydrochloric acid delivered by the hydrochloric acid delivery pump 1 enters; the reaction tank is also provided with a calcium carbonate feeding port, and hydrochloric acid and calcium carbonate react in the reaction tank to generate calcium chloride; the neutralization tank is provided with a calcium hydroxide inlet, and the pH is adjusted to alkaline by adding calcium hydroxide, and metal impurities such as Fe and Mg are separated and removed after forming hydroxide precipitation.

[0020] In this embodiment, the reaction tank is set as a two-stage reaction tank, the first-stage reaction tank is provided with a hydrochloric acid addition port and a calcium carbonate feeding port, and its overflow port is connected to the second-stage reaction tank through a pipeline, the second-stage reaction tank is provided with a calcium carbonate feeding port, and the discharge port of the second-stage reaction tank is connected to the neutralization tank.

[0021] In some embodiments, the filtration equipment may be a plate and frame filter press. The filtrate after plate and frame filtration is a calcium chloride solution, which is further concentrated and granulated, and the filter residue is discharged.

[0022] In other embodiments, a filtrate buffer tank is provided between the filtration apparatus and the flash evaporation tower, where the press filtrate is temporarily stored before flash evaporation and concentration. In more preferred embodiments, an activated carbon decolorization step may be added, where the press filtrate is decolorized with activated carbon before entering the flash evaporation tower.

[0023] In a preferred embodiment, the reaction tank, the neutralization tank, the clarification tank and the filtrate buffer tank are all sealed containers. A stirrer is provided in the reaction tank and the neutralization tank, and the driving motor of the stirrer is an explosion-proof motor.

[0024] In other embodiments, a heat exchanger is further provided outside the flash tower, and a discharge pipe connected to the granulation drying equipment is further provided with a branch pipe, which is connected to the return port of the flash tower after passing through the heat exchanger to form a circulation loop.

[0025] The granulation and drying equipment is preferably a granulation and drying fluidized bed.

[0026] The utility model relates to an apparatus for producing calcium chloride from Mannheim potassium sulfate as a byproduct of low-quality hydrochloric acid, specifically a method for reacting hydrochloric acid with calcium carbonate and neutralizing and removing impurities with calcium hydroxide. The hydrochloric acid and calcium carbonate undergo at least a primary reaction, calcium hydroxide is added for neutralization and impurity removal, and solid residue and filtrate are separated by filter press. The filtrate is flash evaporated to obtain a concentrated filtrate, which is then dried and granulated to obtain anhydrous calcium chloride. The method primarily comprises three steps: neutralization reaction, flash evaporation concentration, and granulation and drying.

[0027] Step 1: Neutralization reaction

[0028] The low-quality hydrochloric acid produced as a by-product of potassium sulfate is transported to the primary reaction tank 2 by the hydrochloric acid delivery pump 1, and calcium carbonate is added to react with it. The mixture is stirred for 30 minutes. The reaction liquid enters the secondary reaction tank 3 from the overflow port at the top of the primary reaction tank to react with calcium carbonate again. After stirring for 30 minutes, it flows into the neutralization tank 4, and calcium hydroxide emulsion is introduced to adjust the pH to 8.0-9.0. After the reaction, a calcium chloride solution is obtained, which is pumped into the clarification tank 7 for clarification by the neutralization tank discharge pump 6. The clarified solution is pumped into the filtration equipment 9 for separation by the clarification tank discharge pump 8 to obtain solid residue and filtrate. The filtrate enters the filtrate buffer tank 10.

[0029] Step 2: Flash Concentration

[0030] The solution in the filtrate buffer tank 10 is fed into the middle feed port of the flash tower 12 through the filtrate delivery pump 11 for flash concentration. The distillation temperature is controlled at 120°C~150°C, and the concentration degree is controlled at 10%~15%. The flash water vapor at the top of the flash tower 12 can be discharged directly. The concentrated filtrate at the bottom of the flash tower 12 is returned to the upper part of the flash evaporation through the flash tower discharge pump 13 through the heat exchanger 14 to achieve the purpose of circulation, and part of it is pumped into the granulation drying fluidized bed 15 from the side.

[0031] Step 3: Granulation and drying

[0032] The concentrated liquid is pumped into a granulation drying fluidized bed for granulation and drying. The drying temperature is controlled at 270°C ~ 300°C to obtain anhydrous calcium chloride with a CaCl2 content of ≥94%.

[0033] Through this device, anhydrous calcium chloride that meets national qualified product standards can be obtained; it solves the problem of low-quality hydrochloric acid retained as a by-product of potassium sulfate and subsidized export. The system is simple, has low operating requirements, and meets industrial conditions.

[0034] The above embodiments are merely illustrative of the technical concepts and features of the present invention. The contents described are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Within the technical scope disclosed by the present invention, equivalent changes or improvements based on the technical solutions and the concepts of the present invention are also encompassed within the scope of protection of the present invention.

Claims

1. A device for producing calcium chloride from Mannheim potassium sulfate as a by-product of low-quality hydrochloric acid, characterized in that: The method comprises at least one primary reaction tank, a neutralization tank, a clarification tank and a filtering device connected in sequence. The filtrate of the filtering device is transported to a flash tower. The discharge pipe at the bottom of the flash tower is connected to a granulation and drying device. The reaction tank is provided with an inlet for adding low-quality hydrochloric acid produced as a by-product of Mannheim potassium sulfate. The reaction tank is also provided with a calcium carbonate feeding port. The neutralization tank is provided with an inlet for adding calcium hydroxide.

2. The device according to claim 1, characterized in that: The reaction tank is two-stage, the first-stage reaction tank is provided with a hydrochloric acid feeding port and a calcium carbonate feeding port, and its overflow port is connected to the second-stage reaction tank through a pipeline, the second-stage reaction tank is provided with a calcium carbonate feeding port, and the discharge port of the second-stage reaction tank is connected to the neutralization tank.

3. The device according to claim 1, characterized in that: The filtering equipment is a plate and frame filter press.

4. The device according to any one of claims 1 to 3, characterized in that: A filtrate buffer tank is also provided between the filtration equipment and the flash tower.

5. The device according to claim 4, characterized in that: The reaction tank, neutralization tank, clarification tank and filtrate buffer tank are all closed containers.

6. The device according to claim 1, characterized in that: A heat exchanger is also provided outside the flash tower, and a branch pipe is provided on the discharge pipe connected to the granulation drying equipment. The branch pipe is connected to the return port of the flash tower after passing through the heat exchanger to form a circulation loop.

7. The device according to claim 1, characterized in that: Agitators are provided in the reaction tank and the neutralization tank, and the driving motor of the agitator is an explosion-proof motor.

8. The device according to claim 1, characterized in that: The granulation and drying equipment is a granulation and drying fluidized bed.

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