CN106176802B - A kind of gypsum processing method - Google Patents

Abstract

The invention discloses a gypsum processing method, which is characterized by comprising the following steps: the processing method adopts a calcined method and comprises the following steps: providing broken gypsum blocks, placing in a suitable container, calcining at 400 deg.C for 30-60min, taking out, cooling, and grinding into powder. The obtained gypsum crystal water can be completely removed, insoluble anhydrite is generated without changing crystal form, the dissolution rate of calcium ions is high, and the antibacterial effect is good.

Description

A kind of gypsum processing method

technical field

The present invention relates to a kind of gypsum processing method, especially the processing method of gypsum forging.

Background technique

Gypsum is sweet, acrid, and cold. Returns the lung and stomach meridians. The raw product has the functions of clearing away heat and purging fire, removing irritability and quenching thirst. For exogenous fever, high fever and polydipsia, cough due to lung heat, hyperactivity of stomach fire, headache, toothache. Calcined gypsum relieves the nature of great cold, avoids injury to the spleen-yang, weakens the effect of clearing away heat and purging fire, increases the astringency, and produces the functions of moisturizing, muscle regeneration, astringing sores, and hemostasis. For external use, it is mainly used to treat ulcers that do not converge, eczema itching, water and fire burns, and traumatic bleeding. Raw and calcined gypsum products are qualitatively different in function, indication and clinical application, so they should be used for different purposes. The 2015 edition of the Chinese Pharmacopoeia classified raw gypsum and calcined gypsum.

Gypsum is a commonly used traditional Chinese medicine. Currently, the Pharmacopoeia contains two specifications of decoction pieces: raw gypsum and calcined gypsum. At first, only raw products were used for mashing. Later, there are processing techniques such as water-flying and re-grinding, which are also to obtain fine powder without heating and forging. Since then, there have been records of techniques such as stir-frying, simmering in the pot, calcining red with fire, and wrapping the fire with paper. The current Pharmacopoeia stipulates that the Ming calcination method is used, which is the closest to the fire calcined red operation, but the specific temperature and time are not specified, and only the crystal water is required to evaporate to the end.

Gypsum is a mineral medicine containing crystal water. The main purpose of calcination is to remove crystal water. Whether it is dehydrated or not is the key to measure the quality of the calcined product and whether it can produce the function of dampness and astringency. The temperature and time of calcination are the key factors affecting the degree of calcination. At present, there is no unified understanding of the research on the calcination temperature of gypsum. The Pharmacopoeia stipulates that the calcination of this kind of traditional Chinese medicine does not require redness, but the crystal water needs to be evaporated to the end, or all of them can be formed into a honeycomb-shaped block solid. Studies have shown that gypsum starts to lose water when heated to 80-90 °C, and can be completely dehydrated and converted into calcined gypsum when it is heated to 225 °C. However, a large number of other literature studies believe that the optimal processing temperature of gypsum is 650 ℃ and above. To sum up, the existing research conclusions are very different.

The gypsum processing method recorded in traditional ancient books has little firepower, and the temperature of simmering and simmering in paper will not be very high. In time, the fire is calcined red. Because firewood was often used in ancient times, the temperature would not be very high.

Therefore, for the temperature and time of calcination, the traditional empirical method makes the operation method not uniform, and even if the same person operates, the quality of each batch of products cannot be guaranteed to be uniform. Moreover, the dissolution rate of calcium ions is uneven, and the antibacterial effect is also unstable.

SUMMARY OF THE INVENTION

The inventors of the present invention have carried out in-depth research on this, and investigated different temperatures (80-950°C, calcination for 1 h) and different times (200, 350, 400°C for 5, 10, 20, 30, 60, 90, 120min) weight loss of calcined products, dissolution of calcium ions in water decoction, change of crystal form and bacteriostatic effect, in order to optimize the best processing conditions from a wide range of time and temperature.

The research results of the present invention show that the raw gypsum starts to lose water when heated at 80°C, the water loss rate is the highest at 120-200°C, and the crystal form changes at 350°C. First, hemihydrate gypsum is generated, and then soluble anhydrite is generated. Gypsum is converted into insoluble anhydrite. The crystal water has just been lost, and when it is converted into soluble anhydrite, the dissolution rate of calcium ions is the highest, and the bacteriostatic effect is the best. When the temperature continued to rise, the dissolution rate of calcium ions decreased, and the bacteriostatic effect was weakened. Therefore, the inventor believes that the optimum processing conditions are the temperature of 300-400°C and the calcination time of 30-60min.

From this point of view, the temperature of 300-400 degrees is also more reasonable. Below 300 degrees, the experimental results clearly show that the crystal water cannot be completely removed.

The present invention provides a new method for processing gypsum.

The applicant has conducted extensive and in-depth research on the method of gypsum processing, thereby completing the present invention.

The present invention provides:

1. a method for gypsum processing, is characterized in that: adopting the calcination method to carry out processing and processing, comprises the following steps:

Provide raw gypsum pieces, put them in a suitable container, calcine at 300-400 ℃ for 30-60min, take out, let cool, and grind into powder.

2. The method according to item 1, wherein the forging temperature is between 350°C and 400°C, and the forging time is 30-60 minutes.

3. The method according to item 2, wherein the forging temperature is about 350° C. and the forging time is about 60 minutes; or the forging temperature is 400° C. and the forging time is 30 minutes.

4. The method according to item 1, wherein the forging temperature is between 300°C and 350°C, and the forging time is 30-60 minutes.

5. The method according to any one of items 1-4, wherein the raw gypsum is washed, dried, crushed, removed of miscellaneous stones, and crushed into coarse powder.

6. The method according to item 5, wherein the forging temperature is about 350° C., and the forging time is about 50-60 min.

7. A method according to item 1, wherein,

Put the gypsum in the calcining pot, turn on the power supply, set the temperature, the lower limit temperature is 300°C, the upper limit temperature is 400°C, and the gypsum calcination time limit is 30-60 minutes;

When the time limit is reached, open the lid and take it out. It is not advisable to stop the fire in the middle of calcination, let it cool, smash it, and then use a pulverizer to make it into a fine powder.

The gypsum crystal water obtained by the invention can be completely removed, and the crystal form has not been changed to generate insoluble anhydrite, the calcium ion dissolution rate is high, and the antibacterial effect is good. The optimal conditions will vary slightly depending on the degree of pulverization and the amount of gypsum.

Description of drawings

Fig.1 TG/DTG curve of gypsum calcined at room temperature-900℃,

Fig. 2 DTA curve of gypsum calcined at room temperature-900℃,

Fig. 3A TG/DTG curve of calcined gypsum at 50℃,

Figure 3B DTA curve of calcined gypsum at 50℃,

Figure 4A TG/DTG curve of calcined gypsum at 80°C,

Figure 4B DTA curve of calcined gypsum at 80°C,

Figure 5A TG/DTG curve of calcined gypsum at 110°C,

Fig. 5B DTA curve of calcined gypsum at 110℃,

Figure 6A TG/DTG curve of calcined gypsum at 140°C,

Fig. 6B DTA curve of calcined gypsum at 140℃,

Figure 7A TG/DTG curve of calcined gypsum at 170°C,

Fig. 7B DTA curve of calcined gypsum at 170℃,

Figure 8A TG/DTG curve of calcined gypsum at 200°C,

Figure 8B DTA curve of calcined gypsum at 200°C,

Figure 9A TG/DTG curve of calcined gypsum at 350°C,

Fig. 9B DTA curve of calcined gypsum at 350°C,

Fig. 10A TG/DTG curve of calcined gypsum at 400℃,

Fig. 10B DTA curve of calcined gypsum at 400℃,

Figure 11A TG/DTG curve of calcined gypsum at 750°C,

Fig. 11B DTA curve of calcined gypsum at 750℃,

Figure 12 XRD patterns of calcined gypsum at different temperatures, the patterns from top to bottom correspond to the temperature on the right side of the figure from high to low,

Fig. 13 Dissolution of calcium ions of calcined gypsum at different temperatures,

Fig. 14 Dissolution of calcium ions in calcined gypsum at different times at 200°C,

Fig. 15 Dissolution of calcium ions in calcined gypsum at different time at 350℃,

Fig. 16 Dissolution of calcium ions in calcined gypsum at different times at 400°C.

Detailed ways

The present invention is described in detail below through specific examples, but should not be construed as limiting the present invention in any way.

Instruments and Materials

Instruments Thermobalance, D/max 2500 powder X-ray diffractometer from Rigaku Corporation, Japan,

Material This product is a sulfate mineral anhydrite gypsum, mainly containing calcium sulfate (CaS04·2H20). After excavation, the miscellaneous stones and sediment are removed.

Example 1

The gypsum processing is carried out by the calcination method, which includes the following steps:

Take raw gypsum fragments, put them in a calcining pot, turn on the power, set the temperature, calcinate at 350 ° C for 60 min, take out, let cool, and grind into powder.

The above process was repeated at 120°C, 200°C, 300°C, 400°C, and 800°C, respectively, to obtain different powders.

In addition, calcination was carried out at 350° C. for 20 minutes, 30 minutes, 90 minutes, and 120 minutes, respectively, and the above-mentioned process was repeated.

Example 2

The gypsum processing is carried out by the calcination method, which includes the following steps:

Take raw gypsum pieces, put them in a calcining pot, turn on the power, set the temperature, calcinate at 400°C for 30 minutes, take them out, let them cool, and grind them into powder.

The above process was repeated at 120°C, 200°C, 300°C, 360°C, and 800°C, respectively, to obtain different powders.

In addition, calcination was carried out at 400° C. for 20 minutes, 30 minutes, 90 minutes, and 120 minutes, respectively, and the above-mentioned process was repeated.

Experimental example 1

1 Thermal stability analysis

Thermogravimetric analysis (TG) is a technique for measuring the mass versus temperature of a substance at a programmed temperature. The instrument used for the thermogravimetric method is a thermobalance, which can continuously record the functional relationship between mass and temperature (TG curve), and derive a derivative thermogravimetric curve (DTG) by derivation of mass against time.

Differential thermal analysis (DTA) is a technique that measures the temperature difference between a sample and a reference (a substance that does not produce any thermal effect within the measurement temperature range) at a programmed temperature. During the experiment, the temperature difference between the sample and the reference sample can be continuously recorded as a function of temperature or time. The temperature difference is the ordinate and the temperature is the abscissa. The peak reflects the exothermic and endothermic process of the sample. The shape, position and corresponding temperature of the peak can be used to qualitatively identify the area ratio of the research object to the heat change, and can be used to determine the heat of reaction semi-quantitatively or quantitatively in some cases. .

1.1 Program temperature gypsum pulverized through a 100-mesh sieve. The powder was placed in a crucible with a sample size of 10 mg for thermal analysis. The heating rate was 10 °C·min-1, and the heating range was room temperature to 900 °C.

The TG curve reflects the weight loss of the sample. It can be seen from Figure 1 that the gypsum starts to lose weight at 80°C, and tends to be flat at 200°C, with a weight loss of 20.6%, which is equivalent to losing two crystal waters. The DTG curve is the derivative of the TG curve with time. It can be seen from Figure 1 that there are two peaks with the fastest weight loss rate between 80 and 200 °C, indicating that the two crystal waters of gypsum are lost step by step. According to the literature, gypsum first loses 3/2 crystal water to form hemihydrate gypsum, and then loses 0.5 crystal water to form dehydrated hemihydrate gypsum. The upward or downward peaks of the DTA curve reflect the exothermic and endothermic processes of the sample. There are two downward peaks at 80-200 °C, indicating that there are two endothermic reactions in gypsum calcination, which is consistent with the DTG curve. Gypsum loses crystal water in this temperature range with an endothermic reaction. The presence of an upward peak at 350°C represents an exothermic reaction, indicating that the crystal form of gypsum has changed. 1.2 The constant temperature calcined gypsum is crushed and passed through a 100-mesh sieve. The powder was placed in a crucible, and the sample size was 10 mg for thermal analysis. The heating rate was 10 °C·min-1, and the temperature was increased to 50, 80, 110, 140, 170, 200, 300, 350, 400, and 750 °C, respectively. After calcination at constant temperature for 1 h. The result is shown in Figure 3-11.

It can be seen from the above results that, after constant temperature calcination for 1 hour, there is no water loss at 50 °C, water loss starts at 80 °C, and the weight loss rate is the fastest at 150-200 °C, and two crystal waters are lost step by step. With the change of crystal form, the trend of TG/DTG and DTA curves of constant temperature calcination for 1h is basically the same.

Experimental example 2

Analysis of Crystal Structure of Gypsum at Different Calcination Temperatures

The phases of the samples calcined at different high temperatures were analyzed using a D/max 2500 powder X-ray diffractometer from Rigaku Corporation to analyze the phase changes and possible new phases during the calcination process, CuKα rays, graphite monochromators, The tube voltage is 30kV, the tube current is 15mA, and the scanning range is 10°-80°. The XRD pattern of gypsum was processed by JADE5.0 software. Figure 12 is the XRD pattern of the sample.

The above XRD patterns are clearly divided into two groups. Taking 350℃ as the boundary temperature, below 350℃, there are characteristic diffraction peaks of CaS04·0.5H20; higher than 350℃, there are characteristic diffraction peaks of soluble anhydrite.

The diffraction peaks at 110, 140, 170, 200, 250, 300°C at 2θ of 14.86°, 29.85°, 32, 42.51° and around 54° and 55° are the characteristic diffraction peaks of CaS04 0.5H20, 350, 400, The diffraction peaks at 450 and 750 °C are almost non-existent, and 31.38°, 36.36°, 41.37°, 52.33°, and 55.83° are characteristic diffraction peaks of CaS04, and the diffraction peaks around 25.65° increase with temperature. increases, the peak height shows an increasing trend, and the diffraction angle shifts to the left. The XRD pattern at 300°C has both the characteristic diffraction peaks of CaS04·0.5H20 and CaS04, which is a good indication of the process of the conversion of CaS04·0.5H20 to CaS04, and the complete transformation of 350°C into soluble anhydrite undergoes a change in crystal form, which is similar to the DTA pattern. meets the.

The data are represented by the interplanar spacing d (Angstrom×10 ^-1 nm), and the relative intensity of diffraction is represented by the relative intensity of peak height I/I ₀ . The main diffraction peaks of calcined gypsum at 110℃ are as follows: 5.9168/45.5, 3.4346/49.1, 2.9800/100.0, 2.7777/53.1, 2.6961/6.9, 2.3223/4.5, 2.2533/4.7, 2.1244/16.4, 2.0980/5.5, 1.8990/6 1.8350/33.7, 1.7276/6.0, 1.6868/13.0, 1.6614/10.1

The main diffraction peaks of calcined gypsum at 140℃ are as follows: 5.9249/50.4, 3.4398/53.8, 2.9820/100.0, 2.7810/57.5, 2.6931/7.0, 2.3236/4.5, 2.2544/4.9, 2.1253/18.8, 2.0999/6.8, 1.8976/7 1.8371/33.6, 1.7276/6.9, 1.6857/14.8, 1.6598/10.4

The main diffraction peaks of calcined gypsum at 170℃ are as follows: 6.0132/62.7, 3.4714/56.0, 3.0056/100.0, 2.8013/57.0, 2.7167/6.9, 2.3331/4.3, 2.2706/4.5, 2.1377/18.1, 2.1100/5.9, 1.9095/6 1.8441/32.0, 1.7330/5.6, 1.6927/14.0, 1.6659/10.1

The main diffraction peaks of calcined gypsum at 200℃ are as follows: 5.9568/53.2, 3.4527/53.2, 2.9917/100.0, 2.7862/57.3, 2.6995/7.2, 2.3270/5.1, 2.2587/5.0, 2.1282/18.9, 2.1027/6.7, 1.9050/6 1.8378/32.5, 1.7281/6.3, 1.6891/14.2, 1.6609/10.4

The main diffraction peaks of calcined gypsum at 250℃ are as follows: 5.9806/50.7, 3.4609/63.4, 2.9957/100.0, 2.7945/55.1, 2.7105/6.6, 2.3294/4.9, 2.2653/4.5, 2.1320/16.2, 2.1064/5.3, 1.9065/6 1.8419/30.8, 1.7294/6.1, 1.6875/11.9, 1.6637/9.4

The main diffraction peaks of calcined gypsum at 300℃ are as follows: 5.9336/20.3, 3.4714/100.0, 2.9917/40.1, 2.8377/12.1, 2.7777/22.0, 2.3213/8.4, 2.1995/7.3, 2.1703/3.2, 2.1282/7.1, 2.0761/4 1.8596/9.5, 1.8406/15.8, 1.7428/8.2, 1.6858/4.2

The main diffraction peaks of calcined gypsum at 350℃ are as follows: 3.4742/100.0, 2.8377/12.2, 2.3155/7.6, 2.2005/7.8, 2.1761/4.4, 2.0769/4.2, 1.8603/7.6, 1.7422/8.7, 1.6402/4.6

The main diffraction peaks of calcined gypsum at 400℃ are as follows: 3.4930/100.0, 2.8483/12.0, 2.3248/7.9, 2.2068/6.4, 2.1782/4.2, 1.8661/7.2, 1.7465/7.7, 1.6456/4.4

The main diffraction peaks of calcined gypsum at 450℃ are as follows: 3.5039/100.0, 2.8537/17.0, 2.4754/4.9, 2.3306/10.5, 2.2109/10.1, 2.1873/5.3, 2.0869/5.6, 1.8696/9.3, 1.7497/9.3, 1.6488/6.8

The main diffraction peaks of calcined gypsum at 750℃ are as follows: 3.4982/100.0, 2.8517/13.2, 2.4727/5.1, 2.3270/10.3, 2.2077/10.1, 2.1821/6.0, 2.0842/5.0, 1.8675/8.4, 1.7483/10.1, 1.6467/6.8

Experimental example 3

Effects of different calcination temperatures and times on the weight loss of gypsum and the dissolution rate of calcium ions in water decoction

Calculation of weight loss: Take 30g of gypsum (with a crucible to weigh and record the total mass before calcination) and calcine at the required temperature and time respectively, take it out, weigh it after cooling, and calculate the weight loss.

Extraction preparation and calcium ion dissolution experiment: Weigh 12.5g of the calcined sample powder respectively, accurately release it, put it in a 1000ml round-bottomed flask, add 250ml of double distilled water, heat and reflux for extraction for 1 h, suction filtration, and wash the flask with double distilled water. Filter residue, combine the filtrate and dilute to volume in a 500ml volumetric flask. Precisely measure 100ml of the extract, add 5ml of potassium hydroxide test solution dropwise, add a small amount of calcein indicator, and titrate with disodium EDTA titration solution (0.05mol/L) until the yellow-green fluorescence of the solution disappears, and Appears orange. Do three parallel experiments and take the average value.

3.1 Different calcination temperatures

Take 30 g of raw gypsum and calcined at 120, 200, 350, 400 and 800 ℃ for 1 h at constant temperature.

Table 1 Weight loss of calcined gypsum at different temperatures

temperature/℃ Before calcination/g After calcination/g Weight loss/g 120 78.91 76.39 2.52 200 79.83 75.03 4.80 350 79.77 73.54 6.23 400 81.44 75.18 6.26 800 81.44 75.16 6.28

The main component of gypsum is CaS04·2H20 (≥95%), and the proportion of crystal water is 20.93%. In this experiment, the mass of 2 crystal water lost is 6.28g, the mass of 3/2 crystal water is 4.71g, the mass of 1 crystal water is 3.14g, and the mass of half crystal water is 1.57g. Since gypsum is not pure calcium sulfate dihydrate, it can be seen from the above table that dehydration can be regarded as complete at 350 °C, and the increase in weight loss at high temperature may be due to the volatilization of organic components in gypsum. According to the literature, gypsum first loses 3/2 crystal water to form hemihydrate gypsum, and then loses 0.5 crystal water to form dehydrated hemi-gypsum. Therefore, the weight loss at 120 °C means that the gypsum part loses 3/2 crystal water, and at 200 °C, it loses all the crystal water. 3/2 crystal water and part 0.5 crystal water.

This is not completely consistent with the TG/DTG curve of gypsum temperature-programmed temperature, which may be affected by the sampling amount of the sample or the heating rate.

Dissolution of calcium ions in calcined gypsum at different temperatures

It can be seen from Figure 13 that with the loss of crystal water, the dissolution rate of calcium ions increases continuously, and the highest temperature is at 400 °C. When the temperature continues to increase, the dissolution rate of calcium ions decreases with the increase of temperature, which may be related to gypsum. High temperature changes from soluble anhydrite to insoluble anhydrite.

3.2 Different calcination time

Take 30g of gypsum and calcined at 200, 350, 400 ℃ for 5, 10, 20, 30, 60, 90, 120min respectively.

Table 3 Weight loss of calcined gypsum at different time at 200℃

It can be seen from Table 3 that with the prolongation of the calcination time, the weight loss continues to increase, and the calcination for 120min still does not achieve complete water loss, which should be the loss of all 3/2 crystal water and part 0.5 crystal water, which is consistent with the experimental results in 3.1. match.

Table 4 Weight loss of calcined gypsum at different time at 350℃

The results showed that the water loss was complete at 60min, which was consistent with the results in 3.1.

Table 5 Weight loss of calcined gypsum at different time at 400℃

In Table 5, when the temperature increases, the time for dehydration is shortened accordingly, and it can be regarded as complete dehydration at 30min.

Dissolution of calcium ions in calcined gypsum at different time at 200℃

Dissolution of calcium ions in calcined gypsum at different time at 350℃

Dissolution of calcium ions in calcined gypsum at different time at 400℃

Combined with the analysis of the weight loss data, the dissolution rate of the three temperatures is low when the weight loss is about 3g (200℃ for 30min, 350℃ for 10min, 400℃ for 10min), and the dissolution rate is the largest when it loses two crystal waters or just loses crystal water. (120min at 200°C, 30min at 400°C). When the crystal water is completely lost, the dissolution rate decreases with the prolongation of calcination time, so it means that the longer the calcination time, the better.

Experimental example 4

Antibacterial experiment of calcined gypsum at different temperatures

Minimum inhibitory concentrations of gypsum calcined products at different temperatures corresponding to different bacterial species

The results showed that the bacteriostatic effect of the three strains was comprehensive, and 300-350 degrees was the best.

By comprehensively considering the TG/DTG and DTA curves of gypsum, the XRD pattern, the weight loss of the calcined product, the dissolution rate of calcium ions in the decoction and the bacteriostatic effect, the inventors concluded that the optimal processing temperature of gypsum is 300-400 ° C Between, the time is 30-60min. Preferably, the processing temperature is about 350° C. and the time is 50-60 min.

The foregoing are merely some of the embodiments of the present invention. For those of ordinary skill in the art, without departing from the inventive concept of the present invention, several modifications and improvements can be made, which all belong to the protection scope of the present invention.

Claims (5)

1. a gypsum processing method, is characterized in that: adopt the calcination method to carry out processing and processing, comprise the following steps: Take the raw gypsum pieces, put them in a suitable container, calcine at 350℃ to 400℃ for 30-60min, take them out, let them cool, and grind them into powder. 2 . The method according to claim 1 , wherein the forging temperature is 350° C. and the forging time is 60 minutes; or the forging temperature is 400° C. and the forging time is 30 minutes. 3 . 3. The method according to claim 1, wherein the raw gypsum is washed, dried, crushed, removed of miscellaneous stones, and crushed into coarse powder. 4. The method according to claim 3, wherein the forging temperature is 350°C, and the forging time is 50-60 min. 5. The method according to claim 1, wherein, Put the gypsum in the calcining pot, turn on the power supply, set the temperature, the lower limit temperature is 350°C, the upper limit temperature is 400°C, and the gypsum calcination time limit is 30-60 minutes; When the time limit is reached, open the lid and take it out. It is not advisable to stop the fire in the middle of calcination, let it cool, smash it, and then use a pulverizer to make it into a fine powder.

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