Method for preparing high-purity calcium hydroxide through carbide slag low-temperature calcination-multi-stage swirl jet flotation

Abstract

The invention aims at providing a method for preparing high-purity calcium hydroxide through carbide slag low-temperature calcination-multi-stage swirl jet flotation, and belongs to the technical field of carbide slag comprehensive utilization. The working process comprises the steps that carbide slag is calcined, water is added to prepare slurry, the slurry is introduced into a multi-stage swirl jet flotation device, and the high-purity calcium hydroxide is obtained; opening the tube flotation device to stir rotational flow, adding a flotation reagent to perform rotational flow type flotation, enabling low-density particle slurry to slowly flow out from an overflow port through a rotational flow force field to form concentrate, enabling medium-density particle slurry to flow out from the inner inverted cone to form middling, enabling the middling to circularly enter the column body, and enabling high-density particle slurry to flow out from the space between the inner inverted cone and the outer inverted cone to form tailings, namely Ca (OH) 2 slurry; carrying out solid-liquid separation on the collected tailing slurry; and drying the solid by a vacuum drying method to obtain a high-purity calcium hydroxide product. The method has the characteristics of good economical efficiency, small occupied area, replacement of a traditional flotation unit, reduction of operation cost and economic cost, and easiness in operation and use.

Description

Technical Field

[0001] The invention belongs to the technical field of comprehensive utilization of carbide slag, and specifically relates to a method for preparing high-purity calcium hydroxide through low-temperature calcination of carbide slag and multi-stage cyclone jet flotation. Background Art

[0002] As a high-calcium secondary resource, dry carbide slag is usually grayish white, densely covered with small holes, and is a powdery material with relatively strong adhesion and water retention. It has important application value in the fields of industry and environmental protection. In recent years, with the development of nanomaterial technology, the use of carbide slag to prepare nano calcium carbonate has become a research hotspot. The main component of carbide slag is calcium hydroxide, which contains impurities such as silicon, aluminum, and iron. These impurities seriously affect its application in the preparation of nano calcium carbonate; the effective component calcium hydroxide in carbide slag will decompose and generate calcium oxide (CaO) when calcined at high temperature, and react with impurity silicon to form insoluble calcium silicate (CaSiO3), thereby reducing the silicon content. However, the traditional high-temperature calcination process is not only energy-intensive, but also has strict requirements on equipment, and is not suitable for large-scale application. Cyclone air flotation technology is an efficient water treatment technology that combines cyclone centrifugal separation technology and air flotation technology. It uses the principle of fluid mechanics to generate high-speed rotating flow inside the cyclone, so that impurities such as suspended matter and oil droplets in the water collide and adhere to bubbles, thereby achieving solid-liquid or liquid-liquid separation. This indicates that cyclone gas flotation technology can be used in the pretreatment stage of carbide slag to improve the purity and recovery rate of calcium hydroxide.

[0003] The multi-stage cyclone jet flotation technology consists of three parts: slurry inlet, column separation section and bubble generation and tube flotation device. The slurry flows from top to bottom, and the floatability deteriorates as the position decreases. The medium-difficult-to-float particles are separated in the upper cyclone, while the extremely difficult-to-float particles form circulating middlings, which serve as the bubble generator medium. In the tube flotation device, after the flotation reagent is added, the bubbles are mixed with the three-phase system and enter the lower layer tangentially, forming a cyclone fluid moving upward. The low-density particles move toward the center and are discharged. The inverted cone structure of the bottom flow outlet separates the slurry into circulating middlings and tailings, which are discharged separately. Summary of the invention

[0004] The present invention aims at the problem that impurities in dry-process carbide slag are difficult to remove, and provides a method for preparing high-purity calcium hydroxide by low-temperature calcination of carbide slag-multi-stage cyclone jet flotation. Organic impurities are decomposed by low-temperature calcination, and then silicide impurities formed by calcination and light components doped in carbide slag are dispersed in a multi-stage cyclone jet flotation device, so as to realize efficient stripping of carbide slag impurities and form a high-purity calcium hydroxide product. The present invention has good economic performance, small footprint, replaces traditional flotation units, and reduces operating costs and economic costs.

[0005] The present invention adopts the following technical solution: A method for preparing high-purity calcium hydroxide by low-temperature calcination of carbide slag and multi-stage cyclone jet flotation, comprising the following steps: The first step is to calcine the carbide slag in a muffle furnace at a calcination temperature of 400-700°C for a calcination time of 0.5-3h; The second step is to add water to the calcined and cooled calcium carbide slag to form a slurry with a solid content of 10%-20%, and pass the slurry into the inlet section of the multi-stage cyclone jet flotation device, open the tube flotation device for ventilation to form a cyclone position, stir the cyclone for 10-20 minutes, and form a circulating medium ore that enters the column; The third step is to add the inhibitor at the reagent adding port, add the primary amine collector after 3-8 minutes, add the foaming agent after 5-10 minutes, and then, after 3-8 minutes, the compressed air inlet is inflated into the column through the injection port; The fourth step is to wait for 10-20 minutes, and the low-density particle slurry moves toward the central axis of the column and upwards through the cyclonic force field, and returns to calmness in the upper layer of the column away from the cyclonic force field, and slowly flows out from the overflow port to form concentrate, and the medium-density particle slurry flows out from the inner inverted cone to form the medium ore circulation into the column, and the high-density particle slurry flows out from between the inner and outer inverted cones to form tailings slurry, that is, Ca(OH)2 slurry; The fifth step is to pass the tailings slurry into the inlet section of the multi-stage cyclone jet flotation device again, open the tube flotation device, stir the cyclone for 10-20 minutes, add the inhibitor at the reagent addition port, add the primary amine collector after 3-8 minutes, and add the frother after 5-10 minutes; after 3-8 minutes, the compressed air inlet is inflated through the jet port into the column, and wait for 10-20 minutes to complete the second stage cyclone flotation; Step 6: The tailings slurry after the second-stage cyclone flotation is passed into the inlet section of the multi-stage cyclone jet flotation device again, the tube flotation device is opened, the cyclone is stirred for 10-20 minutes, the inhibitor is added to the reagent addition port, the primary amine collector is added after 3-8 minutes, and the frother is added after 5-10 minutes; after 3-8 minutes, the compressed air inlet is inflated through the jet port into the column, and the third-stage cyclone flotation is completed after 10-20 minutes; Step 7, separating the collected tailings slurry into solid and liquid; In the eighth step, the solid after solid-liquid separation is dried by vacuum drying to obtain a high-purity calcium hydroxide product.

[0006] Further, the inhibitor in the third step includes sodium hexametaphosphate in an amount of 50-150 g / t; Furthermore, the primary amine collector in the third step includes any one of dodecylamine, octadecylamine and octadecylamine hydrochloride, with an amount of 100-300 g / t.

[0007] Furthermore, the foaming agent in the third step includes pine oil in an amount of 40-80 g / t.

[0008] Furthermore, the solid-liquid separation method in the eighth step includes any one of centrifugal separation, plate and frame filter press separation and rotary drum vacuum filtration separation.

[0009] Wherein, in the second step, the compressed air inlet of the tube flotation device is opened and then not closed.

[0010] The secondary cyclone flotation in the fifth step and the tertiary cyclone flotation in the sixth step may be subjected to more cyclone jet flotation operations according to specific operations.

[0011] The tube flotation device of the present invention is used for introducing air and adding reagents, and circulating the ore into the device and then spraying them into the column together.

[0012] The beneficial effects of the present invention are as follows: According to the physical and chemical properties of carbide slag, the low-temperature calcination in the present invention removes the moisture and organic impurities in the carbide slag, and the CaO formed by calcination is converted into Ca(OH)2 by adding water to make a slurry, and reacts with the impurity silicon to form insoluble calcium silicate (CaSiO3), and then sodium hexametaphosphate and other inhibitors are added to inhibit calcium hydroxide, and primary amine collectors adsorb impurity silicides to make them float upward, and the light components doped in the carbide slag are also removed by cyclone flotation. The tailings formed are the high-purity Ca(OH)2 slurry after impurities are removed. The obtained product is a high-purity calcium hydroxide with a whiteness of 92.8-96.3 and a purity of 94.2%-97.5%.

[0013] The process of the present invention first reduces environmental pollution by calcination, and at the same time combines the cyclone and flotation processes. The specific surface area of ​​the bubbles formed by the pressurized injection is larger than that of the bubbles in the traditional flotation machine, which improves the flotation efficiency; and the technology reduces the economic cost and operating cost. In summary, the process of the present invention is simple, and has obvious energy-saving advantages and strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The multi-stage cyclone jet flotation process flow chart of the present invention; Among them: 1-muffle furnace; 2-inlet section; 3-column; 4-tube flotation device; 5-reagent addition port; 6-compressed air inlet; 7-injection port. DETAILED DESCRIPTION

[0015] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0016] Example 1 A method for preparing high-purity calcium hydroxide by low-temperature calcination of carbide slag and multi-stage cyclone jet flotation, comprising the following steps: a) calcining the carbide slag in a muffle furnace at a temperature of 400°C for 0.5 h; b) adding water to the calcined and cooled calcium carbide slag to form a slurry with a solid content of 10%, passing the slurry into the inlet section of the multi-stage cyclone jet flotation device, opening the tube flotation device 4 for ventilation to form a cyclone position, stirring the cyclone for 10 minutes, forming a circulating medium ore entering the column; c) Add 50 g / t of sodium hexametaphosphate at the reagent adding port, add 100 g / t of octadecylamine hydrochloride 3 minutes later, add 40 g / t of pine oil 5 minutes later, and then, 3 minutes later, inflate the compressed air from the inlet through the injection port into the column; d) Wait for 10 minutes, and the low-density particle slurry will move toward the central axis of the column and upward through the cyclonic force field. It will return to calmness in the upper layer of the column away from the cyclonic force field and slowly flow out from the overflow port to form concentrate. The medium-density particle slurry will flow out from the inner inverted cone to form the medium ore that circulates into the column. The high-density particle slurry will flow out from between the inner and outer inverted cones to form tailings, i.e., Ca(OH)2 slurry. e) The tailings slurry is passed into the inlet section of the multi-stage cyclone jet flotation device again, the tube flotation device is opened, the cyclone is stirred for 10 minutes, 50 g / t of sodium hexametaphosphate is added to the reagent addition port, 100 g / t of octadecylamine is added after 3 minutes, and 40 g / t of pine oil is added after 5 minutes; 3 minutes later, the compressed air inlet is inflated through the jet port into the column, and the second stage cyclone flotation is completed after 10 minutes; f) The tailings slurry after the second-stage cyclone flotation is passed into the inlet section of the multi-stage cyclone jet flotation device again, the tube flotation device is opened, the cyclone is stirred for 10 minutes, 50 g / t of sodium hexametaphosphate is added to the reagent addition port, 100 g / t of octadecylamine hydrochloride is added 3 minutes later, and 40 g / t of pine oil is added 5 minutes later; 3 minutes later, the compressed air is inflated from the compressed air inlet through the jet port 7 into the column, and the third-stage cyclone flotation is completed after 10 minutes; g) separating the collected tailings slurry into solid and liquid; h) the solid is dried by vacuum drying to obtain a high-purity calcium hydroxide product; In the above steps, centrifugal separation is used for solid-liquid separation.

[0017] The calcium hydroxide product prepared in this experimental case is a high-purity calcium hydroxide product with a whiteness of 93.7 and a purity of 94.2%.

[0018] Example 2 The method and workflow are the same as those of Example 1, except that the calcination temperature in step a) is 700° C. and the calcination time is 3 h; the solid content in step b) is 10%, and the stirring time is 20 min; the sodium hexametaphosphate in step c) is 150 g / t, 300 g / t of octadecylamine hydrochloride is added after 8 min, 80 g / t of pine oil is added after 10 min, and 8 min later, air is inflated from the compressed air inlet through the injection port into the column, waiting for 20 min in step d), the time of steps e) and f) is consistent with that of steps c) and d), and the solid-liquid separation method in step g) adopts plate and frame filter press separation.

[0019] The calcium hydroxide product prepared in this implementation case has a whiteness of 96.2 and a purity of 97.4%.

[0020] Example 3 The method and working process are the same as those of Example 1, except that the calcination temperature in step a) is 700° C. and the calcination time is 0.5 h; the solid content in step b) is 20%, and the stirring time is 20 min; the sodium hexametaphosphate in step c) is 100 g / t, 300 g / t of dodecylamine is added after 8 min, 80 g / t of pine oil is added after 10 min, and 8 min later, air is inflated from the compressed air inlet through the injection port into the column, waiting for 20 min in step d), the time of steps e) and f) is consistent with that of steps c) and d), and the solid-liquid separation method in step g) adopts rotary drum vacuum filtration separation.

[0021] The calcium hydroxide product prepared in this implementation case has a whiteness of 92.8 and a purity of 94.9%.

[0022] Example 4 The method and working process are the same as those of Example 1, except that the calcination temperature in step a) is 700° C. and the calcination time is 3 h; the solid content in step b) is 10%, and the stirring time is 20 min; the sodium hexametaphosphate in step c) is 100 g / t, 300 g / t of octadecylamine hydrochloride is added after 8 min, 40 g / t of pine oil is added after 10 min, and after 8 min, air is inflated from the compressed air inlet through the injection port into the column, waiting for 10 min in step d), the time of step e) and step f) is consistent with that of step c) and step d), and centrifugal separation is adopted as the solid-liquid separation method in step g).

[0023] The calcium hydroxide product obtained in this implementation case has a whiteness of 95.4 and a purity of 96.8%.

[0024] Example 5 The method and working process are the same as those of Example 1, except that the calcination temperature in step a) is 700° C. and the calcination time is 3 h; the solid content in step b) is 10%, and the stirring time is 20 min; the sodium hexametaphosphate in step c) is 150 g / t, 300 g / t of octadecylamine hydrochloride is added after 8 min, 40 g / t of pine oil is added after 10 min, and 8 min later, air is inflated from the compressed air inlet through the injection port into the column, waiting for 20 min in step d), the time of step e) and step f) is consistent with that of step c) and step d), and centrifugal separation is adopted as the solid-liquid separation method in step g).

[0025] The calcium hydroxide product obtained in this implementation case has a whiteness of 96.3 and a purity of 97.5%.

[0026] Example 6 The method and working process are the same as those of Example 1, except that the calcination temperature in step a) is 500° C. and the calcination time is 3 h; the solid content in step b) is 10%, and the stirring time is 20 min; the sodium hexametaphosphate in step c) is 50 g / t, 100 g / t of octadecylamine hydrochloride is added after 8 min, 40 g / t of pine oil is added after 10 min, and 8 min later, air is inflated from the compressed air inlet through the injection port into the column, waiting for 20 min in step d), the time of step e) and step f) is consistent with that of step c) and step d), and centrifugal separation is adopted as the solid-liquid separation method in step g).

[0027] The calcium hydroxide product obtained in this implementation case has a whiteness of 92.9 and a purity of 94.6%.

[0028] Example 7 The method and working process are the same as those of Example 1, except that the calcination temperature in step a) is 700° C. and the calcination time is 3 h; the solid content in step b) is 10%, and the stirring time is 20 min; the sodium hexametaphosphate in step c) is 50 g / t, 100 g / t of octadecylamine hydrochloride is added after 8 min, 40 g / t of pine oil is added after 10 min, and 8 min later, air is inflated from the compressed air inlet through the injection port into the column, waiting for 20 min in step d), the time of step e) and step f) is consistent with that of step c) and step d), and centrifugal separation is adopted as the solid-liquid separation method in step g).

[0029] The calcium hydroxide product obtained in this implementation case has a whiteness of 95.3 and a purity of 95.5%.

[0030] Example 8 The method and working process are the same as those of Example 1, except that the calcination temperature in step a) is 700° C. and the calcination time is 3 h; the solid content in step b) is 20%, and the stirring time is 20 min; the sodium hexametaphosphate in step c) is 100 g / t, 300 g / t of octadecylamine hydrochloride is added after 8 min, 40 g / t of pine oil is added after 10 min, and 8 min later, air is inflated from the compressed air inlet through the injection port into the column, waiting for 20 min in step d), the time of step e) and step f) is consistent with that of step c) and step d), and centrifugal separation is adopted as the solid-liquid separation method in step g).

[0031] The calcium hydroxide product obtained in this implementation case has a whiteness of 94.5 and a purity of 94.8%.

Claims

1. A method for preparing high-purity calcium hydroxide by low-temperature calcination of carbide slag and multi-stage cyclone jet flotation, characterized in that: The steps include: The first step is to calcine the carbide slag in a muffle furnace at a calcination temperature of 400-700°C for a calcination time of 0.5-3h; The second step is to add water to the calcined and cooled calcium carbide slag to form a slurry with a solid content of 10%-20%, and pass the slurry into the inlet section of the multi-stage cyclone jet flotation device, open the tube flotation device for ventilation to form a cyclone position, stir the cyclone for 10-20 minutes, and form a circulating medium ore that enters the column; The third step is to add the inhibitor at the reagent adding port, add the primary amine collector after 3-8 minutes, add the foaming agent after 5-10 minutes, and then, after 3-8 minutes, the compressed air inlet is inflated into the column through the injection port; The fourth step is to wait for 10-20 minutes, and the low-density particle slurry moves toward the central axis of the column and upwards through the cyclonic force field, and returns to calmness in the upper layer of the column away from the cyclonic force field, and slowly flows out from the overflow port to form concentrate, and the medium-density particle slurry flows out from the inner inverted cone to form the medium ore circulation into the column, and the high-density particle slurry flows out from between the inner and outer inverted cones to form tailings slurry, that is, Ca(OH)2 slurry; The fifth step is to pass the tailings slurry into the inlet section of the multi-stage cyclone jet flotation device again, open the tube flotation device, stir the cyclone for 10-20 minutes, add the inhibitor at the reagent addition port, add the primary amine collector after 3-8 minutes, and add the frother after 5-10 minutes; after 3-8 minutes, the compressed air inlet is inflated through the jet port into the column, and wait for 10-20 minutes to complete the second stage cyclone flotation; Step 6: The tailings slurry after the second-stage cyclone flotation is passed into the inlet section of the multi-stage cyclone jet flotation device again, the tube flotation device is opened, the cyclone is stirred for 10-20 minutes, the inhibitor is added to the reagent addition port, the primary amine collector is added after 3-8 minutes, and the frother is added after 5-10 minutes; after 3-8 minutes, the compressed air inlet is inflated through the jet port into the column, and the third-stage cyclone flotation is completed after 10-20 minutes; Step 7, separating the collected tailings slurry into solid and liquid; In the eighth step, the solid after solid-liquid separation is dried by vacuum drying to obtain a high-purity calcium hydroxide product.

2. The method for preparing high-purity calcium hydroxide by low-temperature calcination of carbide slag-multi-stage cyclone jet flotation according to claim 1, characterized in that: The inhibitor in the third step includes sodium hexametaphosphate in an amount of 50-150 g / t.

3. The method for preparing high-purity calcium hydroxide by low-temperature calcination of carbide slag-multi-stage cyclone jet flotation according to claim 1, characterized in that: The primary amine collector in the third step includes any one of dodecylamine, octadecylamine and octadecylamine hydrochloride, and the dosage is 100-300 g / t.

4. The method for preparing high-purity calcium hydroxide by low-temperature calcination of carbide slag-multi-stage cyclone jet flotation according to claim 1, characterized in that: The foaming agent in the third step includes pine oil in an amount of 40-80 g / t.

5. The method for preparing high-purity calcium hydroxide by low-temperature calcination of carbide slag-multi-stage cyclone jet flotation according to claim 1, characterized in that: The solid-liquid separation method in the eighth step includes any one of centrifugal separation, plate and frame filter press separation and rotary drum vacuum filtration separation.

Images