CN106830042B - A kind of method that the ultra-fine carbonic acid fine particle calcium carbonate of rhombohedron shape is prepared using Weihe north Ordovician limestone - Google Patents

Abstract

The invention discloses a kind of method that ultra-fine carbonic acid fine particle calcium carbonate is prepared using Weihe north Ordovician limestone, including：Weihe north Ordovician limestone is crushed, clean, dry, is sieved, obtains the particle of 1.6mm 2.0mm；Above-mentioned particle is calcined into 60min in 1000 DEG C, obtains active lime；Above-mentioned active lime and 90 DEG C of water are mixed and made into 5.6wt% lime slurries；Above-mentioned lime slurry is placed in container, is put into ultrasonic oscillation device, sodium laurate is added into container, is passed through CO₂Gas, stirring, 20 DEG C of reaction temperature；When pH is down to 7, stopping is passed through CO₂And ultrasonic oscillation device is closed, continue to stir 20min；Filtering, washing, to solute drying, grind up to ultra-fine carbonic acid fine particle calcium carbonate.The invention has the beneficial effects that：Using Weihe north Ordovician limestone as raw material, using carbonizatin method, and crystal control agent sodium laurate is added before charing, increases gas distributor and ultrasonic technique in carbonization process, has prepared function admirable, added value height, in the ultra-fine carbonic acid fine particle calcium carbonate product of rhombohedron shape.

Description

A method of preparing rhombohedral ultrafine light calcium carbonate from Ordovician limestone in Weibei method

technical field

The invention relates to a method for preparing ultrafine light calcium carbonate, in particular to a method for preparing rhombohedral ultrafine light calcium carbonate by using Weibei Ordovician limestone, and belongs to the technical field of chemical industry.

Background technique

Ultrafine light calcium carbonate refers to the powder particles prepared by chemical methods with a particle size in which molecular clusters and macroscopic particles are mixed. The particle size of ultra-fine light calcium carbonate is between 0.02μm-0.1μm; non-toxic, odorless, low hygroscopicity, usually stored in a dry environment; sedimentation volume is 2.4mL/g-2.8mL/g, molecular weight is 100 , specific surface area ≥ 18m ² /g, melting point of 1339°C, relative density of 2.45-2.50; at room temperature (25°C), the solubility in water is very small, and the pH value is between 8.0-10.2; under normal pressure, when the temperature The chemical properties are stable at ≤550°C, and it is easy to decompose when the temperature is between 800°C and 900°C; it can undergo exothermic reactions with various strong acids and produce a certain amount of CO ₂ .

Ultrafine light calcium carbonate has special effects such as macroscopic quantum and small size. These characteristics of ultrafine light calcium carbonate make it show obvious advantages in magnetic properties, catalytic properties, dispersibility, thixotropy and leveling, etc. , Therefore, the use of ultrafine light calcium carbonate in the production process of rubber products, paper products, sealant materials, cement, medicinal materials, food, etc., can significantly increase capacity, reinforce, and reduce costs.

At present, domestic methods for synthesizing ultrafine light calcium carbonate include: carbonization method, precipitation method, double decomposition method, emulsion method, hydrolysis synthesis method, bionic method, etc. In 2013, Mantilaka, University of Peradeniya, Sri Lanka, etc. used the bubbling carbonization method to successfully synthesize amorphous calcium carbonate using dolomite as raw material, sucrose as calcium ion extractant, and polyacrylic acid solution as stabilizer. In 2012, Kojima of Japan University used the ultrasonic atomization mixed reaction method (SARM) to atomize the reaction solution under ultrasonic-assisted conditions to prepare a new type of amorphous calcium carbonate.

my country's ultra-fine light calcium carbonate production ranks second in the world, but the product quality lags far behind developed countries, such as large particle size, wide particle size distribution, low whiteness, difficulties in industrial mass production, irregular crystal morphology, poor dispersion, etc. Due to the defects, my country still needs to import a large number of high-grade ultra-fine light calcium carbonate products from abroad to meet the needs of the industry.

In the Ordovician limestone in the Weibei area, the content of CaO is high and the content of harmful components (iron, manganese, etc.) is low. Using it to prepare ultrafine light calcium carbonate has natural advantages. On the one hand, the limestone reserves in this area are large and the price is low. Low production cost can solve the problem of low-value utilization of limestone resources, increase the economic added value of limestone, give full play to the advantages of limestone resources, and broaden the application field of limestone; on the other hand, limestone is used to prepare ultra-fine light calcium carbonate, It can reduce the environmental pollution caused by the application of limestone in the construction field, and strengthen the environmental protection.

At present, the morphology of ultrafine light calcium carbonate produced in my country includes: spherical, needle-shaped, rod-shaped, flake-shaped, chain-shaped, cube-shaped, and amorphous, etc., but there are rare reports on the synthesis of ultra-fine calcium carbonate with other special shapes. In particular, there is no report on the preparation of rhombohedral superfine light calcium carbonate from Ordovician limestone in Weibei.

Contents of the invention

The object of the present invention is to provide a method for preparing rhombohedral superfine light calcium carbonate with high purity, good whiteness, fine particle size, good dispersibility and rhombohedral shape by using Ordovician limestone in Weibei.

In order to achieve the above object, the present invention adopts the following technical solutions:

A method for preparing rhombohedral superfine light calcium carbonate using Ordovician limestone in Weibei, characterized in that it specifically includes the following steps:

Step 1: crushing the Ordovician limestone in Weibei, and then washing and removing impurities, drying, and sieving to obtain raw material particles with a particle size of 1.6mm-2.0mm;

Step 2: Put the above-mentioned raw material particles in a box-type resistance furnace, and calcinate at 1000°C for 60 minutes to obtain high-activity lime;

Step 3: Mix the above-mentioned highly active lime with hot water at 90° C. in a mass ratio of 1:10, stir for 4 hours, pass through a 400-mesh sieve, refine into a lime emulsion with a mass concentration of 5.6%, and leave the lime emulsion for 30 hours;

Step 4: Place the above-mentioned prepared lime emulsion in a container and put it into an ultrasonic oscillator, add the crystal form control agent sodium laurate into the above-mentioned container, the addition amount of sodium laurate is 1.5g/L, and then pass into _CO2 gas and control the _CO2 flow rate at 200mL/min, start the stirrer and control the stirring speed at 1000r/min, control the reaction temperature at 20°C, track and record the reaction process with a pH meter and a conductivity meter;

Step 5: When the pH drops to 7, stop feeding CO ₂ gas and turn off the ultrasonic oscillator, and continue stirring for 20 minutes;

Step 6: filter, wash, vacuum-dry and grind the obtained solute to obtain superfine light calcium carbonate.

The aforementioned method is characterized in that, in step 1, the Ordovician limestone in Weibei is crushed using a jaw crusher.

The aforementioned method is characterized in that, in step 2, the heating rate of the aforementioned box-type resistance furnace is set to 10° C./min.

The aforementioned method is characterized in that, in step 4, when introducing CO ₂ gas, a gas distributor is used.

The aforementioned method is characterized in that the opening diameter of the aforementioned gas distributor is 0.8 mm.

The benefits of the present invention are: using Weibei Ordovician limestone as raw material, adding crystal form control agent sodium laurate, adopting the improved carbonization process of adding gas distributor and ultrasonic technology in the carbonization process, the preparation has excellent performance (higher purity) High, whiteness, fine particle size), high added value, rhombohedral superfine light calcium carbonate products.

Description of drawings

Figure 1 is a scanning electron microscope analysis diagram of a product prepared by a traditional carbonization method;

Fig. 2 is the scanning electron microscope analysis diagram of the product prepared in embodiment 1;

Fig. 3 is the X-ray diffraction analysis figure of the rhombohedral superfine light calcium carbonate product that embodiment 1 prepares;

Fig. 4 is the particle size distribution figure of the rhombohedral superfine light calcium carbonate product that embodiment 1 prepares;

Fig. 5 is the infrared spectrogram of rhombohedral superfine light calcium carbonate product prepared by embodiment 1;

Fig. 6 is the scanning electron microscope analysis diagram of the product prepared in embodiment 2;

Fig. 7 is the rhombohedral shape superfine light calcium carbonate product X-ray diffraction analysis figure that embodiment 2 prepares;

Fig. 8 is that the rhombohedral superfine light calcium carbonate that embodiment 2 prepares produces particle size distribution figure;

Fig. 9 is the infrared spectrum analysis figure of rhombohedral superfine light calcium carbonate product prepared in embodiment 2;

Fig. 10 is the scanning electron microscope analysis figure of the product prepared in embodiment 3;

Fig. 11 is the X-ray diffraction analysis figure of rhombohedral superfine light calcium carbonate product prepared in embodiment 3;

Fig. 12 is the particle size distribution figure of rhombohedral superfine light calcium carbonate product prepared by embodiment 3;

Fig. 13 is the infrared spectrum analysis diagram of the rhombohedral ultrafine light calcium carbonate product prepared in Example 3.

Detailed ways

The present invention will be specifically introduced below in conjunction with the accompanying drawings and specific embodiments.

Example 1

In this example, the limestone used is the No. 1 limestone sample (thick layered, light gray, massive) of the Ordovician Majiagou Formation in Tongchuan. According to the operating requirements in the national standard GB/T3286-2012, the The contents of CaO, MgO, SiO ₂ , Al ₂ O ₃ and Fe ₂ O ₃ were determined. Through analysis and determination, the main chemical components in limestone are shown in Table 1.

Table 1 Contents of main chemical components in limestone

The method for preparing superfine light calcium carbonate by adopting No. 1 limestone sample of Ordovician Majiagou Formation in Tongchuan comprises the following steps:

Step 1: The No. 1 limestone sample of the Ordovician Majiagou Formation in Tongchuan was crushed with a jaw crusher, and then cleaned, dried, and sieved to obtain raw material particles with a particle size of 1.6mm-2.0mm.

Step 2: put the above-mentioned raw material particles into a box-type resistance furnace for calcination, set the heating rate at 10°C/min, and calcine at 1000°C for 60min to obtain active lime, and the measured activity of the active lime is 365mL.

Step 3: Mix active lime and hot water at 90°C in a mass ratio of 1:10, stir for 4 hours, pass through a 400-mesh sieve, refine the lime emulsion with a mass concentration of 5.6%, and let the lime emulsion stand for 30 hours.

Step 4: Take 200mL of the above-mentioned reconciled lime emulsion and place it in a four-necked bottle with a capacity of 500mL, place the four-necked bottle in an ultrasonic oscillator, and place the gas distributor connected with the ventilation catheter, the conductivity meter, the pH meter and Insert the stirrers into the four-necked bottles respectively, and put them into the ultrasonic oscillator, add the crystal form control agent sodium laurate into the above-mentioned container, the addition amount of sodium laurate is 1.5g/L, then pass in _CO2 gas, use the open A gas distributor with a hole diameter of 0.8mm, control the flow rate of _CO2 at 200mL/min, start the stirrer, control the stirring speed at 1000r/min, control the reaction temperature at 20°C, track and record with a pH meter and a conductivity meter reaction process.

Step 5: When the pH drops to about 7, stop feeding CO ₂ gas and turn off the ultrasonic oscillator, and continue stirring for about 20 minutes.

Step 6: filter, wash, vacuum-dry and grind the obtained solute to obtain superfine light calcium carbonate.

The comparison between the performance of the product prepared in Example 1 and the performance of the product prepared by the traditional carbonization method is shown in Table 2.

The performance comparison of the products obtained by two kinds of carbonization methods in table 2

It can be seen from Table 2 that the particle size of the product prepared in Example 1 is significantly reduced, and the pH value is reduced, while the whiteness of the product does not change compared with that of the product prepared by the traditional carbonization method.

The morphology of the product prepared by the traditional carbonization method and the morphology of the product prepared in Example 1 are shown in Figure 1 and Figure 2 respectively.

As can be seen from Figures 1 and 2, the products prepared by the traditional carbonization method have various and irregular shapes, uneven particle size, and a large particle size of about 0.5 μm. After the improved carbonization method of the present invention is adopted, the prepared products The shape is rhombohedral and uniform, and the particle size is uniform and small, about 0.06 μm.

It can be seen that the improved carbonization method of the present invention can promote the carbonization reaction, is beneficial to increase the crystal nucleation rate, and makes the prepared product have excellent performance.

The X-ray diffraction analysis results of the rhombohedral ultrafine light calcium carbonate product prepared in Example 1 are shown in Figure 3.

It can be seen from Figure 3 that the values of all main characteristic diffraction peaks at 2θ are: 23.06°, 29.4°, 36.0°, 39.42°, 43.14°, 47.56°, 48.54°, 57.36°, 60.72°, 64.62°, 77.58° , the crystal planes corresponding to the main characteristic diffraction peaks at 2θ can correspond to the crystal planes of standard calcite (JCPDS: 05-0586), which are (012), (104), (110), (113), ( 202), (018), (116), (122), (124), (300), (134), etc.

It can be seen that the main mineral of the ultrafine light calcium carbonate product prepared in Example 1 is calcite.

The particle size distribution of the rhombohedral superfine light calcium carbonate product prepared in Example 1 is shown in Figure 4.

It can be seen from Figure 4 that 90% of the particle size of the prepared ultrafine light calcium carbonate is concentrated in the range of 0.03 μm-0.1 μm, where d ₁₀ =0.03 μm, d ₅₀ =0.06 μm, d ₉₀ =0.09 μm, The average particle size of the product is 0.06μm, which meets the particle size requirements of the first-class industrial superfine light calcium carbonate.

The infrared spectrum analysis of the rhombohedral ultrafine light calcium carbonate product prepared in Example 1 is shown in Figure 5.

As can be seen from Figure 5, the main absorption peaks in the infrared spectrum analysis diagram are at 3451.75cm ^-1 , 1440.40cm ^-1 , 1792.24cm ^-1 , 875.93cm ^-1 and 713.69cm ^-1 and the characteristic absorption peaks of calcite crystal calcium carbonate Corresponding.

It can be seen that the main mineral composition of the ultrafine light calcium carbonate product prepared in Example 1 is calcite, which is consistent with the XRD detection results. Among them, the broad absorption peak at 3451.75cm ^-1 is caused by the existence of adsorbed water in the ultrafine light calcium carbonate; the strong absorption peak at 1440.40cm ^-1 is the asymmetry of the C-O bond in the ultrafine light calcium carbonate stretching vibration peak; the absorption peak at 1796.24cm ^-1 is the C=O vibration peak of CO ₃ ^2- in ultrafine light calcium carbonate; the absorption peaks at 875.93cm ^-1 and 713.69cm ^-1 are ultrafine light calcium carbonate The bending vibration peak of the C-O bond in calcium.

The rhombohedral ultrafine light calcium carbonate product prepared in Example 1 was compared with the index specified in the industrial ultrafine light calcium carbonate standard.

Table 3 Example 1 prepares rhombohedral superfine light calcium carbonate quality index contrast

It can be seen from Table 3 that the whiteness of the ultrafine light calcium carbonate product prepared in Example 1 is 95%, the pH value is 9.0, the iron content is 0.06%, the density is 2.57g/cm ³ , and the average particle diameter is 0.06 μm, completely It complies with the regulations of the first-class product in the index of industrial ultra-fine light calcium carbonate.

Example 2

In this example, the limestone used is the No. 2 limestone sample (thick layered, light gray, massive) of the Ordovician Majiagou Formation in Tongchuan. According to the operating requirements in the national standard GB/T3286-2012, the The contents of CaO, MgO, SiO ₂ , Al ₂ O ₃ and Fe ₂ O ₃ were determined. Through analysis and determination, the contents of main chemical components in limestone are shown in Table 4.

Table 4 Contents of main chemical components in limestone

The method for preparing superfine light calcium carbonate by adopting the No. 2 limestone sample of the Ordovician Majiagou Formation in Tongchuan comprises the following steps:

Step 1: The No. 2 limestone sample of the Ordovician Majiagou Formation in Tongchuan is crushed with a jaw crusher, and then cleaned, dried, and sieved to obtain raw material particles with a particle size of 1.6mm-2.0mm.

Step 2: Put the above-mentioned raw material particles into a box-type resistance furnace for calcination, set the heating rate at 10°C/min, and calcine at 1000°C for 60min to obtain active lime, and the measured activity of the active lime is 368mL.

Step 3: Mix highly active lime with hot water at 90°C in a mass ratio of 1:10, stir for 4 hours, pass through a 400-mesh sieve, refine it into a lime emulsion with a mass concentration of 5.6%, and let the lime emulsion stand for 30 hours.

Step 4: Take 200mL of the above-mentioned reconciled lime emulsion and place it in a four-necked bottle with a capacity of 500mL, place the four-necked bottle in an ultrasonic oscillator, and place the gas distributor connected with the ventilation catheter, the conductivity meter, the pH meter and Insert the stirrers into the four-necked bottles respectively, and put them into the ultrasonic oscillator, add the crystal form control agent sodium laurate into the above-mentioned container, the addition amount of sodium laurate is 1.5g/L, then pass in _CO2 gas, use the open A gas distributor with a hole diameter of 0.8mm, control the flow rate of _CO2 at 200mL/min, start the stirrer, control the stirring speed at 1000r/min, control the reaction temperature at 20°C, track and record with a pH meter and a conductivity meter reaction process.

Step 5: When the pH drops to about 7, stop feeding CO ₂ gas and turn off the ultrasonic oscillator, and continue stirring for about 20 minutes.

Step 6: filter, wash, vacuum-dry and grind the obtained solute to obtain superfine light calcium carbonate.

The morphology of the product prepared in Example 2 is shown in Figure 6.

It can be seen from Fig. 6 that after adopting the improved carbonization method of the present invention, the prepared product has rhombohedral and uniform morphology, uniform particle size and small particle size, about 0.05 μm.

It can be seen that the improved carbonization method of the present invention can promote the carbonization reaction, increase the crystal nucleation rate, and make the prepared product have excellent performance.

The X-ray diffraction analysis results of the rhombohedral ultrafine light calcium carbonate product prepared in Example 2 are shown in Figure 7.

It can be seen from Figure 7 that the values of the main characteristic diffraction peaks of the sample at 2θ are 23.06°, 29.4°, 36.0°, 39.42°, 43.14°, 44.04°, 47.56°, 48.54°, 57.36°, 60.72°, 64.62° , 77.58°, and the diffraction crystal planes corresponding to the main characteristic diffraction peaks at 2θ can all correspond to the crystal planes of standard calcite (JCPDS: 05-0586), which are (012), (104), (110), ( 113), (202), (024), (018), (116), (122), (124), (300), (134).

It can be seen that the main mineral of the superfine light calcium carbonate product prepared in embodiment 2 is calcite.

The particle size distribution of the rhombohedral ultrafine light calcium carbonate product prepared in Example 2 is shown in Figure 8.

It can be seen from Figure 8 that 90% of the prepared rhombohedral ultrafine light calcium carbonate has a product particle size concentrated in the range of 0.04 μm-0.09 μm, where d ₁₀ =0.04 μm, d ₅₀ =0.05 μm, d ₉₀ = 0.08μm, the particle size of the obtained product is relatively uniform, the particle size is small, and the average particle size is about 0.05μm.

The infrared spectrum analysis of the rhombohedral ultrafine light calcium carbonate product prepared in Example 2 is shown in Figure 9.

It can be seen from Figure 9 that the rhombohedral ultrafine light calcium carbonate product prepared in Example 2 has strong characteristic absorption peaks at 1440.40cm ^-1 , 1792.14cm ^-1 , 875.93cm ^-1 and 713.69cm ^-1 , and Corresponds to the characteristic peaks in the standard calcite spectrum (Sadtler).

The above description shows that the main mineral composition of the sample prepared in Example 2 is calcite, which is consistent with the X-ray diffraction analysis results.

The rhombohedral ultrafine light calcium carbonate product prepared in Example 2 was compared with the index specified in the industrial ultrafine light calcium carbonate standard.

The rhombohedral shape superfine light calcium carbonate quality index comparison that table 5 embodiment 2 prepares

As can be seen from Table 5, the particle size, specific surface area, whiteness, pH value, etc. of the ultrafine light calcium carbonate product prepared in Example 2 all meet the basic requirements of the first-class product of industrial ultrafine light calcium carbonate.

Example 3

In this embodiment, the limestone used is the No. 3 limestone sample (thick layer, light gray, massive) of the Ordovician Majiagou Formation in Tongchuan. According to the operation requirements in the national standard GB/T3286-2012, the The contents of CaO, MgO, SiO ₂ , Al ₂ O ₃ and Fe ₂ O ₃ were measured, and the contents of main chemical components in limestone were obtained through analysis and determination, as shown in Table 6.

Table 6 Contents of main chemical components in limestone

The method for preparing superfine light calcium carbonate by adopting the No. 3 limestone sample of the Ordovician Majiagou Formation in Tongchuan comprises the following steps:

Step 1: The No. 3 limestone sample of the Ordovician Majiagou Formation in Tongchuan was crushed with a jaw crusher, and then cleaned, dried, and sieved to obtain raw material particles with a particle size of 1.6mm-2.0mm.

Step 2: Put the above-mentioned raw material particles in a box-type resistance furnace for calcination, set the heating rate at 10°C/min, and calcine at 1000°C for 60 minutes to obtain active lime, and the measured activity of the active lime is 365mL.

Step 3: Mix active lime and hot water at 90°C in a mass ratio of 1:10, stir for 4 hours, pass through a 400-mesh sieve, refine the lime emulsion with a mass concentration of 5.6%, and let the lime emulsion stand for 30 hours.

Step 4: Take 200mL of the above-mentioned reconciled lime emulsion and place it in a four-necked bottle with a capacity of 500mL, place the four-necked bottle in an ultrasonic oscillator, and place the gas distributor connected with the ventilation catheter, the conductivity meter, the pH meter and Insert the stirrers into the four-necked bottles respectively, and put them into the ultrasonic oscillator, add the crystal form control agent sodium laurate into the above-mentioned container, the addition amount of sodium laurate is 1.5g/L, then pass in _CO2 gas, use the open A gas distributor with a hole diameter of 0.8mm, control the flow rate of _CO2 at 200mL/min, start the stirrer, control the stirring speed at 1000r/min, control the reaction temperature at 20°C, track and record with a pH meter and a conductivity meter reaction process.

Step 5: When the pH drops to about 7, stop feeding CO ₂ gas and turn off the ultrasonic oscillator, and continue stirring for about 20 minutes.

Step 6: filter, wash, vacuum-dry and grind the obtained solute to obtain superfine light calcium carbonate.

The morphology of the product prepared in Example 3 is shown in Figure 10.

It can be seen from Figure 10 that after adopting the improved carbonization method of the present invention, the prepared product has a rhombohedral shape, uniform particle size, and a small particle size of about 0.05 μm.

The X-ray diffraction spectrum of the rhombohedral ultrafine light calcium carbonate product prepared in Example 3 is shown in Figure 11.

It can be seen from Figure 11 that the values of the main characteristic diffraction peaks of the sample at 2θ are: 23.06°, 29.4°, 36.0°, 39.42°, 43.14°, 44.04°, 47.56°, 48.54°, 57.36°, 60.72°, 64.62° °, 77.58°, the diffraction crystal planes corresponding to the main characteristic diffraction peaks at 2θ can correspond to the crystal planes of standard calcite (JCPDS: 05-0586), respectively (012), (104), (110), (113), (202), (024), (018), (116), (122), (124), (300), (134).

It can be seen that the main mineral composition of the superfine light calcium carbonate product prepared in Example 3 is calcite.

The particle size distribution of the rhombohedral ultrafine light calcium carbonate product prepared in Example 3 is shown in Figure 12.

It can be seen from Figure 12 that in the rhombohedral ultrafine light calcium carbonate product prepared in Example 3, 90% of the particle size is concentrated in the range of 0.04 μm-0.09 μm, where d ₁₀ =0.04 μm, d ₅₀ =0.05 μm , d ₉₀ =0.08μm, the particle size of the product is relatively uniform, the particle size is small, and the average particle size is 0.05μm, which meets the particle size requirements of the first-class industrial superfine light calcium carbonate.

The infrared spectrum analysis diagram of the rhombohedral ultrafine light calcium carbonate product prepared in Example 3 is shown in Figure 13.

It can be seen from Figure 13 that the rhombohedral ultrafine light calcium carbonate product prepared in Example 3 has strong characteristic absorption peaks at 1440.40cm ^-1 , 1792.14cm ^-1 , 875.93cm ^-1 and 713.69cm ^-1 . Corresponds to the characteristic peaks in the standard calcite spectrum (Sadtler).

The above description shows that the main mineral composition of the rhombohedral ultrafine light calcium carbonate product prepared in Example 3 is calcite, which is consistent with the X-ray diffraction analysis results.

The rhombohedral ultrafine light calcium carbonate product prepared in Example 3 was compared with the index specified in the industrial ultrafine light calcium carbonate standard.

Table 7 Example 3 prepares rhombohedral superfine light calcium carbonate quality index contrast

As can be seen from Table 7, the particle size, specific surface area, whiteness, pH value, etc. of the ultrafine light calcium carbonate product prepared in Example 3 all meet the basic requirements of the first-class product of industrial ultrafine light calcium carbonate.

In summary, the present invention adopts carbonization method to prepare superfine light calcium carbonate, and has added crystal form control agent sodium laurate (addition is 1.5g/L) before carbonization reaction, has increased ultrasonic technology ( Improve the dispersibility of ultrafine light calcium carbonate particles, reduce the particle size) and gas distributor (accelerate the mass transfer and heat transfer of the reaction process, shorten the carbonization time), and the prepared ultrafine light calcium carbonate product has excellent performance ( Higher purity, better whiteness, higher particle dispersibility, finer particle size), rhombohedral shape, completely in line with the regulations of the first-class product in the index of industrial ultra-fine light calcium carbonate, and has great development potential.

It should be noted that the above-mentioned embodiments do not limit the present invention in any form, and all technical solutions obtained by means of equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims (3)

1. a method utilizing Weibei Ordovician limestone to prepare rhombohedral superfine light calcium carbonate, is characterized in that, specifically comprises the following steps: Step 1: crushing the Ordovician limestone in Weibei, and then cleaning and removing impurities, drying, and sieving to obtain raw material particles with a particle size of 1.6mm-2.0mm; Step 2: Put the above-mentioned raw material particles in a box-type resistance furnace, and calcinate at 1000°C for 60 minutes to obtain high-activity lime; Step 3: Mix the above-mentioned highly active lime with hot water at 90° C. in a mass ratio of 1:10, stir for 4 hours, pass through a 400-mesh sieve, refine it into a lime emulsion with a mass concentration of 5.6%, and leave the lime emulsion for 30 hours; Step 4: Place the above-mentioned prepared lime emulsion in a container, and put it into an ultrasonic oscillator, add the crystal form control agent sodium laurate in the container, the addition amount of sodium laurate is 1.5g/L, and then use The gas distributor is fed with _CO2 gas and the flow rate of _CO2 is controlled at 200mL/min. The opening diameter of the gas distributor is 0.8mm. The stirrer is started and the stirring speed is controlled at 1000r/min, and the reaction temperature is controlled at 20°C. Use pH meter and conductivity meter to track and record the reaction process; Step 5: When the pH drops to 7, stop feeding CO ₂ gas and turn off the ultrasonic oscillator, and continue stirring for 20 minutes; Step 6: filter, wash, and vacuum-dry and grind the obtained solute to obtain superfine light calcium carbonate. 2. The method according to claim 1, characterized in that, in step one, the Ordovician limestone in Weibei is broken and adopted a jaw crusher. 3. The method according to claim 1, characterized in that, in step 2, the heating rate of the box-type resistance furnace is set to 10° C./min.