USE OF RED MUD AS A RAW MATERIAL FOR THE PREPARATION OF PORCELAIN CLAY

Abstract

The present invention relates to the technical field of solid waste utilization, and in particular relates to the use of red mud as a raw material for preparing porcelain clay. Particularly, a preparation method for porcelain clay comprises the following steps: A) mixing red mud and an acid solution, and carrying out a reaction to obtain a salt solution having a pH value of 4-6.8; B) carrying out filter pressing on the solution obtained in step A) so as to control the mass content of water to be not higher than 50%, then introducing compressed air, and carrying out drying with the compressed air; C) mixing water and the solid obtained after the drying with compressed air, and carrying out filter pressing again; D) drying and burning the solid obtained after the filter pressing in step C); and E) carrying out iron removal on the burned material obtained in step D) to obtain porcelain clay. By researching, the present applicant found that processing red mud via such steps described above can utilize the vast majority of components in red mud and thus produce high-quality porcelain clay with very little waste residues and waste water generated thereby.

Description

1 / 14 “USE OF RED MUD AS A RAW MATERIAL FOR THE PREPARATION OF PORCELAIN CLAY”

[0001] This application claims priority over Chinese Patent Application No. 202410706666.2, entitled USE OF RED MUD AS RAW MATERIAL FOR PREPARING PORCELAIN CLAY, filed on June 3, 2024, with the National Intellectual Property Administration of China, which is incorporated herein by reference in its entirety. FIELD

[0002] The present disclosure relates to the technical field of the use of solid waste and, in particular, to the use of red mud as a raw material for the preparation of porcelain clay. BACKGROUND

[0003] Alumina production generates a large amount of waste, exceeding 100 million tons per year in China. The waste has a high iron content and is red, hence the name red mud. The main components of red mud are alumina, silica, iron oxide, titanium oxide, calcium oxide, sodium oxide, potassium oxide, etc. It is urgent to make use of red mud and transform waste into valuable resources. There are basically two ways to utilize red mud. One is to extract high-value substances, such as titanium dioxide or some rare metals, etc., to obtain economic profits. However, the problem is that this method still produces a lot of waste, making it difficult to implement in practice. The other is to utilize most of the substances in the red mud, producing little waste and wastewater. This is the ideal way, but how to use it is still a subject under study in this field. SUMMARY

[0004] In view of this, the technical problem to be solved by the present disclosure is to allow the use of red mud as a raw material for the preparation of porcelain clay. In the present disclosure, most of the Petition 870250070677, dated 11 / 08 / 2025, p. 11 / 32 2 / 14 of the substances present in red mud can be used to prepare higher-performance porcelain clay, and little waste and wastewater are produced.

[0005] The present disclosure provides for the use of red mud as a raw material for the preparation of porcelain clay.

[0006] The present disclosure also provides a method for the preparation of porcelain clay, which comprises the following steps:

[0007] A) Mix and react red mud and an acidic solution to obtain a saline solution with a pH value of 4 to 6.8;

[0008] B) subject the solution obtained in step A) to filter pressing and control the water content by mass so that it does not exceed 50%; and then introduce compressed air for air pressure drying;

[0009] C) Mix the air-pressed dry solid with water and subject it to pressing through a filter again;

[0010] D) dry and cauterize the filter-pressed solid from step C); and

[0011] E) remove the iron from the cauterized material in step D) to obtain porcelain clay.

[0012] Preferably, in step a), the red mud comprises 6% to % by mass of Na2O, 22% to 27% by mass of Al2O3, 20% to 25% by mass of SiO2, 7% to 12% by mass of Fe2O3, 2% to 7% by mass of TiO2, 11% to 16% by mass of CaO and 1% to 2% by mass of K2O; the red mud has a Ca / S ratio of 0.3 to 0.8:1; and the red mud has an N / S ratio of 0.1 to 0.6:1.

[0013] Preferably, in step A), the acid in the acidic solution includes at least one of hydrochloric acid, oxalic acid, phosphoric acid, and sulfuric acid; and

[0014] the acidic solution has a mass concentration of 2% to 12%.

[0015] Preferably, in step A), the mass ratio between the acid solution and the red mud is 6 to 12:1; and

[0016] the mass concentration of soluble salt in the saline solution is 0.5% to 1.2%. Petition 870250070677, dated 11 / 08 / 2025, page 12 / 32 3 / 14

[0017] Preferably, in step B), the amount of compressed air is 4 kg / cm2 to 30 kg / cm2; and

[0018] the mass content of soluble salt in the filter-pressed filtrate is 0.5% to 1.2%.

[0019] Preferably, in step C), the mass ratio between the air-pressure dried solid and water is 1:5 to 10; and

[0020] the mass content of soluble salt in the mixed solution is from 0.065% to 0.14%.

[0021] Preferably, in step C), the mass content of water in the solid after pressing by filter again is < 50%; and

[0022] the mass content of soluble salt in the filtrate after pressing through the filter again is 0.07% to 0.15%.

[0023] Preferably, in step D), drying is carried out at a temperature of 120 °C to 150 °C; and the dry solid has a water content of 1% to 10%.

[0024] Preferably, in step D), cauterization is carried out at a temperature of 600 °C to 1200 °C for a period of 2 min to 2 h.

[0025] Preferably, in step E), the iron mass content in the porcelain clay obtained after iron removal is 2.5% to 3.5%.

[0026] The present disclosure provides for the use of red mud as a raw material for the preparation of porcelain clay. Specifically, the method for preparing porcelain clay comprises: A) mixing and reacting red mud and an acidic solution to obtain a saline solution with a pH value of 4 to 6.8; B) filter-pressing the solution obtained in step A) and controlling the water content by mass so that it does not exceed 50%; and then introducing compressed air for air-pressure drying; C) mixing the air-pressure-dried solid with water and filter-pressing again; D) drying and cauterizing the filter-pressed solid in step C); and E) removing iron from the cauterized material in step D) to obtain porcelain clay. Through research, it was found that, when treating red mud according to the steps mentioned above, most of the substances Petition 870250070677, dated 11 / 08 / 2025, page 13 / 32 4 / 14 of the material contained in red mud can be used to prepare higher-performance porcelain clay, and little waste and wastewater is produced. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 shows a particle size distribution of porcelain clay obtained in Example 1 of the present disclosure;

[0028] Figure 2 shows a particle size distribution of porcelain clay obtained in Example 2 of the present disclosure. DETAILED DESCRIPTION

[0029] Hereafter, the technical solutions of the present disclosure will be described clearly and completely together with examples of the present disclosure. Apparently, the examples described are only a part of the embodiments of the present disclosure, rather than all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present disclosure, without any creative work, are covered within the scope of protection of the present disclosure.

[0030] The present disclosure provides for the use of red mud as a raw material for the preparation of porcelain clay.

[0031] The present disclosure also offers a method for preparing porcelain clay, comprising the steps of:

[0032] A) Mix and react red mud and an acidic solution to obtain a saline solution with a pH value of 4 to 6.8;

[0033] B) subject the solution obtained in step A) to filter pressing and control the water content by mass so that it does not exceed 50%; and then introduce compressed air for air pressure drying;

[0034] C) Mix the air-pressed dry solid with water and subject it to pressing through a filter again;

[0035] D) dry and cauterize the filter-pressed solid from step C);

[0036] E) remove the iron from the cauterized material in step D) to obtain porcelain clay.

[0037] In stage A): Petition 870250070677, dated 11 / 08 / 2025, p. 14 / 32 5 / 14

[0038] Red mud and acidic solution are mixed and reacted to obtain a saline solution with a pH value of 4 to 6.8.

[0039] In some embodiments of the present disclosure, the red mud comprises 6% to 10% by mass of Na2O, 22% to 27% by mass of Al2O3, 20% to 25% by mass of SiO2, 7% to 12% by mass of Fe2O3, 2% to 7% by mass of TiO2, 11% to 16% by mass of CaO and 1% to 2% by mass of K2O. The red mud has a Ca / S (mass ratio) of 0.3 to 0.8:1. The red mud has an N / S (mass ratio) of 0.1 to 0.6:1. The red mud has a water content of 10% to 60%, such as 39.9%.

[0040] In some embodiments of the present disclosure, the acid in the acidic solution includes at least one of hydrochloric acid, oxalic acid, phosphoric acid, and sulfuric acid. The acidic solution has a mass concentration of 2% to 12%, such as 2%.

[0041] The mass ratio between the acid solution and the red mud is 6 to 12:1, as are 8:1 and 6:1.

[0042] After mixing water, red mud, and acid solution, the sodium oxide in the red mud reacts with the acid to generate a soluble salt. At this point, the red mud is completely dispersed in the solution in the form of a paste, and the mass concentration of soluble salt in the resulting saline solution is 0.5% to 1.2%, such as 0.8% and 0.79%. Specifically, the saline solution has a pH value of 5.

[0043] The reaction is carried out at a temperature of 2 °C to 40 °C, such as 35 °C and 20 °C, for a period of 0.5 h to 5 h, such as 1 h to 3 h.

[0044] In stage B):

[0045] the solution obtained in step A) is pressed by a filter, and the water content by mass in the filter cake is controlled to not exceed 50%; then, compressed air is introduced for air pressure drying.

[0046] Filter pressing is carried out in a plate and frame filter press. In some embodiments of the present disclosure, the water content by mass is controlled to be less than 40%. Petition 870250070677, dated 11 / 08 / 2025, page 15 / 32 6 / 14

[0047] In some embodiments of the present disclosure, the amount of compressed air is from 4 kg / cm2 to 30 kg / cm2, such as 20 kg / cm2 and 10 kg / cm2.

[0048] In some embodiments of the present disclosure, the mass content of soluble salts in the filter-pressed filtrate is from 0.5% to 1.2%, such as 1.02% and 0.99%. The mass content of calcium chloride in the filter-pressed filtrate is from 0.01% to 0.12%, such as 0.01% and 0.096%.

[0049] In some embodiments of the present disclosure, after filter pressing, the method further comprises: removing calcium chloride from the filtrate and then performing reverse osmosis treatment.

[0050] The method for removing calcium chloride from the filtrate comprises:

[0051] The calcium chloride content in the filtrate is determined by a calcium ion detector, and sodium carbonate is added to generate a precipitate of calcium carbonate and sodium chloride, and the clear topwater is subjected to reverse osmosis treatment.

[0052] The molar ratio between the added sodium carbonate and the calcium chloride in the filtrate is 1:1.

[0053] After removing calcium chloride from the filtrate, the mass content of calcium chloride in the filtrate is < 400 ppm, such as 20 ppm.

[0054] After reverse osmosis treatment, the mass content of soluble salts in the produced water is < 150 ppm, such as 100 ppm and 150 ppm. The water produced by reverse osmosis can be reused in step C) and mixed with the dried solid by air pressure. The mass content of soluble salts in the concentrated water after reverse osmosis is 5% to 12%, and is used for other purposes.

[0055] In step C):

[0056] the air-pressed dried solid is mixed with water and pressed through a filter again.

[0057] In some embodiments of the present disclosure, the mass ratio between the air-pressure dried solid and water is from 1:5 to 10, as well as 1:6. The mass content of soluble salts in the mixed solution is from 0.065% to 0.14%, as well as 0.09%. Petition 870250070677, dated 11 / 08 / 2025, page 16 / 32 7 / 14 and 0.11%.

[0058] According to the present disclosure, the air-pressed dried solid is mixed with water to further remove soluble salts.

[0059] In some embodiments of the present disclosure, the water content by mass in the solid after pressing by filter again is < 50 %.

[0060] In some embodiments of the present disclosure, the mass content of soluble salts in the filtrate after filter pressing again is from 0.07% to 0.15%, such as 0.15% and 0.14%. The filtrate after filter pressing can be reused in step A).

[0061] In stage D):

[0062] the solid pressed by the filter in step c) is dried and cauterized.

[0063] In some embodiments of the present disclosure, drying is carried out at a temperature of 120 °C to 150 °C, such as 130 °C. The dry solid has a water content of 1% to 10%, such as 5.2%.

[0064] After drying, it also includes: grinding. The particle size of the ground particles does not exceed 100 μm.

[0065] In some embodiments of the present disclosure, cauterization is performed at a temperature of 600 °C to 1200 °C, such as 1000 °C; and the duration is from 2 min to 2 h, such as 1 h.

[0066] In stage E):

[0067] Iron is removed from the cauterized material in step D) to obtain porcelain clay.

[0068] There is no special limitation regarding the method for removing iron in the present disclosure. In some embodiments of the present disclosure, the method for removing iron comprises:

[0069] the materials are blown between a plurality of cylindrical magnetic rods by airflow to remove iron.

[0070] The materials are blown between a plurality of cylindrical magnetic rods by airflow, and the strongly magnetic material is attracted to the magnetic rods, and the non-magnetic material or the weakly magnetic material is blown away. Petition 870250070677, dated 11 / 08 / 2025, page 17 / 32 8 / 14 by the airflow, so that the two are separated.

[0071] After the removal of iron, the mass content of iron in the porcelain clay obtained is 2.5% to 3.5%, as well as 2.9%.

[0072] In some embodiments of the present disclosure, the porcelain clay comprises 33% to 34% by mass of Al2O3, 29% to 32% by mass of SiO2, 9% to 11% by mass of Fe2O3, 6% to 7% by mass of TiO2, 6% to 8% by mass of CaO and 0.6% to 0.7% by mass of Na2O.

[0073] In order to better illustrate the present disclosure, the use of the red mud provided by the present disclosure as a raw material for the preparation of porcelain clay will be described below in detail, together with examples, which should not be considered as a limitation to the scope of protection of the present disclosure.

[0074] The raw materials used in the following examples are all commercial products.

[0075] Example 1

[0076] The red mud was taken from a site in Shanxi, and its water content was 39.9%.

[0077] Some components in red mud are shown in Table 1. Table 1. Some components of red mud. Component Name Al2O3 SiO2 Fe2O3 TiO2 CaO Mass content 24.923% 22.218% 9.623% 4.958% 13.235% Component Name Na2O K2O Ca / SN / S Mass content 8.044% 1.527% 0.596% 0.362%

[0078] Preparation of porcelain clay:

[0079] in a circular storage tank, 96 were added Petition 870250070677, dated 11 / 08 / 2025, p. 18 / 32 9 / 14 tons of acidic solution (a mixed solution of hydrochloric acid and phosphoric acid) with a mass concentration of 2%, followed by the addition of 12 tons of red mud; the mixture was reacted at 35 °C for 1 h to obtain a saline solution with a pH value of 5; the mass concentration of soluble salts in the saline solution was 0.8%;

[0080] the saline solution was fed into a plate and frame filter press for filter pressing, and the water content by mass in a filter cake was controlled to be 50%; after the completion of the filter pressing, compressed air was introduced for air pressure drying; the amount of compressed air was 20 kg / cm2; the mass content of soluble salts in the filter-pressed filtrate was 1.02%, and the mass content of calcium chloride in the filter-pressed filtrate was 0.01%;

[0081] after filter pressing, the calcium chloride content in the filtrate was determined using a calcium ion detector, and an equimolar amount of sodium carbonate was added to generate a precipitate of calcium carbonate and sodium chloride, and the mass content of calcium chloride in the upper clear water was 20 ppm, and reverse osmosis treatment was performed; after reverse osmosis treatment, the mass content of soluble salts in the produced water was 100 ppm, and the produced water was reused in step 3); the mass content of soluble salts in the concentrated water after reverse osmosis was 8%;

[0082] 3) The air-pressed dried solid was mixed with water and filter-pressed again using a plate and frame filter press; the mass ratio between the air-pressed dried solid and water was 1:6; the mass content of soluble salts in the mixed solution was 0.09%; the mass content of water in the solid after filter-pressing again was 49.7%; the mass content of soluble salts in the filtrate after filter-pressing again was 0.15%, and the filtrate was reused in step 1);

[0083] 4) After the filter-pressed solid from step 3) was dried at 130 °C, the weight was 8.71 kg and the water content was 5.2%; it was then crushed, and the Petition 870250070677, dated 11 / 08 / 2025, page 19 / 32 10 / 14 particle size after grinding did not exceed 100 μm; then, cauterization was performed at 1000 °C for 1 h.

[0084] 5) The material cauterized in step 4) was blown between a plurality of cylindrical magnetic rods by airflow to remove the iron in order to obtain porcelain clay. The iron content by mass in the porcelain clay was 2.9%.

[0085] After detection, it was found that the remaining residue was 0.61 kg, the yield of porcelain clay was 84.2%, the solids conversion rate was 89.9%, and 62 L of water were used.

[0086] Some components in porcelain clay are shown in Table 2. Table 2. Some components in porcelain clay. Component Name Al2O3 SiO2 Fe2O3 TiO2 CaO Mass content 33.436% 29.913% 9.709% 6.071% 7.321% Component Name Na2O K2O Ca / SN / S Mass content 0.661% 1.923% 0.245% 0.022%

[0087] As can be seen in Tables 1 and 2, most of the sodium was removed and the remaining components remained after the red mud was treated according to the present disclosure. The main components of the finished product are similar to those of porcelain clay, and the titanium oxide content is high, which serves to optimize the porcelain. Based on all test indices, it meets the requirements of porcelain clay.

[0088] After detecting the finished porcelain clay, it can be determined that:

[0089] the mass content of soluble salts was 0.32% (the detection equipment was a conductivity meter); Petition 870250070677, dated 11 / 08 / 2025, p. 20 / 32 11 / 14

[0090] weight loss on calcination: 1.8% (the detection equipment was a muffle furnace);

[0091] apparent density of finished porcelain clay: 0.445 g / ml (the detection equipment was the apparent density detector).

[0092] The average particle size of the finished porcelain clay was 8.08 μm, which was equivalent to 1,700 mesh. Details of the particle size distribution can be seen in the figure. Figure 1 is a particle size distribution of porcelain clay obtained in Example 1 of the present disclosure.

[0093] A porcelain factory carried out an application test of this sample, and the situation was good.

[0094] Example 2

[0095] The components of red mud are the same as in Example 1.

[0096] Preparation of porcelain clay:

[0097] 1) In a circular storage tank, 80 tons of acidic solution (a mixed solution of sulfuric acid and oxalic acid) with a mass concentration of 0.2% were added, followed by the addition of 13 tons of red mud; the mixture was reacted at 20 °C for 3 h to obtain a saline solution with a pH value of 6; the mass concentration of soluble salts in the saline solution was 0.79%;

[0098] 2) the saline solution was fed into a plate and frame filter press for filter pressing, and the water content by mass in the filter cake was controlled to be 49.3%; after the completion of the filter pressing, compressed air was introduced for air pressure drying; the amount of compressed air was 10 kg / cm2; the mass content of soluble salts in the filter-pressed filtrate was 0.99%, and the mass content of calcium chloride in the filter-pressed filtrate was 0.096%;

[0099] After filter pressing, the calcium chloride content in the filtrate was determined using a calcium ion detector, and an equimolar amount of sodium carbonate was added to generate a precipitate of Petition 870250070677, dated 11 / 08 / 2025, page 21 / 32 12 / 14 calcium carbonate and sodium chloride, and the mass content of calcium chloride in the upper clear water was 20 ppm, and reverse osmosis treatment was performed; after reverse osmosis treatment, the mass content of soluble salts in the produced water was 150 ppm, and the produced water was reused in step 3);

[0100] 3) The air-pressed dried solid was mixed with water and filter-pressed again using a plate and frame filter press; the mass ratio between the air-pressed dried solid and water was 1:9; the mass content of soluble salt in the mixed solution was 0.11%; the mass content of water in the solid after filter-pressing again was 49.3%; the mass content of soluble salts in the filtrate after filter-pressing again was 0.14%, and the filtrate was reused in step 1);

[0101] 4) After the filter-pressed solid from step 3) was dried at 120 °C, the weight was 9.63 kg and the water content was 4.8%; then it was ground into particles, and the particle size after grinding did not exceed 100 μm; then cauterization was carried out at 1200 °C for 30 min.

[0102] 5) The material cauterized in step 4) was blown between a plurality of cylindrical magnetic rods by airflow to remove the iron to obtain 9.37 kg of porcelain clay. The iron content by mass in the porcelain clay was 3.0%.

[0103] After detection, it was found that the remaining residue was 0.56 kg, the yield of porcelain clay was 85.2%, the solids conversion rate was 89.7%, and 68 L of water were used.

[0104] Some components in porcelain clay are shown in Table 3. Petition 870250070677, dated 11 / 08 / 2025, page 22 / 32 13 / 14 Table 3. Some components in porcelain clay. Component Name Al2O3 SiO2 Fe2O3 TiO2 Mass content 33.58% 31.46% 10.07% 6.068% Component Name CaO Na2O Mass content 6.51% 0.659%

[0105] As can be seen in Table 1 and Table 3, most of the sodium was removed and the remaining components remained after the red mud was treated according to the present disclosure. The main components of the finished product are similar to those of porcelain clay, and the titanium oxide content is high, which serves to optimize the porcelain. Based on all test indices, it meets the requirements of porcelain clay.

[0106] After detecting the finished porcelain clay, it is possible to know:

[0107] the mass content of soluble salts was 0.34% (the detection method was the conductivity meter);

[0108] weight loss on calcination: 2.0% (the detection equipment was a muffle furnace);

[0109] apparent density of finished porcelain clay: 0.451 g / ml (the detection equipment was the apparent density detector).

[0110] The average particle size of the finished porcelain clay was 10 μm, which was equivalent to 1600 mesh. Details of the particle size distribution can be seen in the figure. Figure 2 is a particle size distribution of porcelain clay obtained in Example 2 of the present disclosure.

[0111] A porcelain factory carried out an application test of this sample, and the situation was good. Petition 870250070677, dated 11 / 08 / 2025, page 23 / 32 14 / 14

[0112] The description of the examples above serves only to help understand the method and central idea of ​​the present revelation. Various modifications in these modalities will be evident to those skilled in the art, and the generic principles defined herein can be implemented in other modalities without departing from the spirit or scope of the present revelation. Therefore, the present revelation is not limited to the modalities described herein, but must be in accordance with the broader scope compatible with the principle and new features revealed herein. Petition 870250070677, dated 11 / 08 / 2025, p. 24 / 32

Claims

1 / 2 CLAIMS 1. Use of red mud as a raw material characterized as being for the preparation of porcelain clay.

2. Method for preparing porcelain clay, characterized by comprising the steps of: A) mixing and reacting red mud and an acidic solution to obtain a saline solution with a pH value of 4 to 6.8; B) filter-pressing the solution obtained in step A) and controlling the water content by mass so that it does not exceed 50%; and then introducing compressed air for air-pressure drying; C) mixing the air-pressure-dried solid with water and filter-pressing again; D) drying and cauterizing the filter-pressed solid from step C); and E) removing iron from the cauterized material from step D) to obtain porcelain clay.

3. Method according to claim 1, characterized in that, in step A), the red mud comprises 6% to 10% by mass of Na2O, 22% to 27% by mass of Al2O3, 20% to 25% by mass of SiO2, 7% to 12% by mass of Fe2O3, 2% to 7% by mass of TiO2, 11% to 16% by mass of CaO and 1% to 2% by mass of K2O; the red mud has a Ca / S ratio of 0.3 to 0.8:1; and the red mud has an N / S ratio of 0.1 to 0.6:

1.

4. Method according to claim 1, characterized in that, in step A), the acid in the acidic solution includes at least one of hydrochloric acid, oxalic acid, phosphoric acid, and sulfuric acid; and the acidic solution has a mass concentration of 2% to 12%.

5. Method according to claim 1, characterized in that, in step A), the mass ratio between the acid solution and the red mud is 6 to 12:1; and the mass concentration of soluble salt in the saline solution is 0.5% to 1.2%.

6. Method according to claim 1, characterized in that, in step B), the quantity of compressed air is from 4 kg / cm2 to 30 kg / cm2; and the mass content of soluble salt in the filter-pressed filtrate is from 0.5% to 1.2%.

7. Method according to claim 1, characterized in that, in step C), the mass ratio between the air-pressure dried solid and water is 1:5 to 10; and the mass content of soluble salt in the mixed solution is 0.065% to 0.14%.

8. Method according to claim 1, characterized in that, in step C), the water content by mass in the solid after pressing by filter again is < 50%; and the soluble salt content by mass in the filtrate after pressing by filter again is from 0.07% to 0.15%.

9. Method according to claim 1, characterized in that, in step D), drying is carried out at a temperature of 120 °C to 150 °C; the dry solid has a water content of 1% to 10%; cauterization is carried out at a temperature of 600 °C to 1200 °C for a period of 2 min to 2 h.

10. Method according to claim 1, characterized in that, in step E), the mass content of iron in the porcelain clay obtained after iron removal is 2.5% to 3.5%. Petition 870250070677, dated 11 / 08 / 2025, pp. 26 / 32

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