Klebsiella variicola ZF-01 and application of Klebsiella variicola ZF-01 in leaching of iron element in iron-rich kaolin

Abstract

The invention relates to a Klebsiella variicola ZF-01 strain and an application thereof. The strain is preserved in the Guangdong Microbial Culture Collection Center, the address of the preservation unit is the 5th floor of the building 59, No.100 Courtyard, Xianlie Middle Road, Guangzhou, the preservation time is November 05, 2025, and the preservation number is GDMCC No.66771. According to the method disclosed by the invention, the deep effect between the Klebsiella variicola and the minerals is utilized, and iron minerals are dissolved by using metabolites of the iron reducing bacteria, so that crystal lattices of the minerals are destroyed, so that impurity components are dissolved out, and a new thought is provided for promoting the development of kaolin iron removal and whitening towards a green, efficient and low-carbon direction.

Description

Technical Field

[0001] This invention relates to the field of deep processing of non-metallic minerals, specifically to a strain of Klebsiella heterotrophus and its application in leaching iron from iron-rich kaolin. Background Technology

[0002] Kaolin is a type of clay or claystone primarily composed of kaolinite group minerals, with minor amounts of non-clay minerals such as quartz, feldspar, iron minerals, titanium minerals, and organic matter. Due to its unique physical and chemical properties, kaolin is widely used in ceramics, papermaking, rubber, plastics, refractory materials, and petroleum refining.

[0003] The whiteness of kaolin is a crucial indicator of its application value. Generally, the iron content in kaolin is the primary factor affecting its whiteness. Iron oxides, hydroxides, and hydrated oxides often impart yellow to red coloration to kaolin, influencing not only its natural whiteness but also its calcined whiteness. Therefore, removing iron impurities from kaolin plays a vital role in its optimal use.

[0004] The state of iron in kaolin is the main factor determining the iron removal method. Currently, both domestically and internationally, the state of iron in kaolin is divided into two types: one is present in the kaolinite crystal lattice, called structural iron; the other exists as independent iron minerals, called free iron (including surface-impregnated iron and fine-grained crystalline iron). The iron removed by kaolin for iron removal and whitening is free iron, mainly including minerals such as magnetite, hematite, limonite, siderite, pyrite, ilmenite, and jaundice.

[0005] The commonly used iron removal and whitening methods are as follows:

[0006] 1. Magnetic separation: This method utilizes the magnetic difference between iron minerals and kaolin to separate magnetic minerals (such as magnetite, hematite, limonite, and ilmenite) using a magnetic field. It has the advantages of being environmentally friendly, low-cost, pollution-free, and suitable for large-scale production, but it is less effective for non-magnetic or weakly magnetic iron minerals.

[0007] 2. Reduction bleaching method: This method uses sodium dithionite (Na2S2O4, sodium hydrosulfite) at a pH of 2-3 to reduce sparingly soluble ferric oxides to soluble ferrous salts, which are then removed through a washing process. This method is widely used for deep whitening of kaolin and significantly improves whiteness. However, this method has a bottleneck in iron removal rate for low-grade kaolin with high Fe2O3 content, and the reagent cost is high. The use of sulfuric acid and sodium dithionite generates acidic waste gas and wastewater, posing environmental pollution problems.

[0008] 3. Magnetic separation-reduction bleaching combined method: This method has the advantages of reducing acid consumption and high overall efficiency, but it still cannot get rid of the environmental pollution caused by acid bleaching.

[0009] For iron-rich kaolin with high iron content, the above methods are not ideal for iron removal and whitening, or the amount of reagents used is greatly increased, making it difficult to utilize low-grade kaolin resources in a high-value manner.

[0010] Biological mineral processing refers to a technology that utilizes microorganisms such as bacteria to enrich, separate, extract, and recycle useful components from minerals and waste. Microbial methods are characterized by low cost, low energy consumption, and relatively low environmental pollution. However, the application of microbial purification technology in the kaolin industry is rarely reported. Summary of the Invention

[0011] The purpose of this invention is to provide a strain of Klebsiella heterotropha ZF-01 and its application in leaching iron from iron-rich kaolin.

[0012] A strain of Klebsiella heterotropha ( Klebsiella variicola ZF-01, this strain is deposited at the Guangdong Provincial Center for Microbial Culture Collection, located at 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, on July 28, 2025, with accession number GDMCC No. 66771.

[0013] Application of the above-mentioned strains in removing iron from iron-rich kaolin.

[0014] Furthermore, it includes the following steps: S1. Prepare a suspension of Klebsiella pneumoniae ZF-01; S2. After mixing iron-rich kaolin, bacterial suspension, water, carbon source, and nitrogen source, leach and culture the mixture to remove iron from the iron-rich kaolin.

[0015] Furthermore, based on the mass ratio, the ratio of iron-rich kaolin: bacterial suspension: water: carbon source: nitrogen source = 1:0.001-0.003:0.3-0.4:0.003-0.005:0.001-0.003; The carbon source is one of starch, cellulose, molasses, sodium acetate, mannitol, sucrose, maltose, xylose, and lactose. The nitrogen source is one of the following: peptone, beef extract, yeast powder, soybean meal, NH4Cl4, potassium nitrate, ammonium nitrate, or glutamic acid.

[0016] Furthermore, the leaching culture was carried out at a temperature of 15-45℃ for 3-12 days.

[0017] A method for removing iron from iron-rich kaolin through bioleaching includes the following steps: S1. Prepare a bacterial suspension of Klebsiella pneumoniae ZF-01 as described in claim 1; S2. After mixing iron-rich kaolin, bacterial suspension, water, carbon source, and nitrogen source, the mixture is cultured for a period of time to complete the leaching reaction. S3. After the leaching reaction is complete, the raw kaolin ore slurry is taken out, screened, and then the kaolin coarse concentrate slurry is obtained. The kaolin coarse concentrate slurry is then classified and dewatered in sequence to obtain iron-removed kaolin.

[0018] Furthermore, in S2, the mass ratio of iron-rich kaolin: bacterial suspension: water: carbon source: nitrogen source is 1:0.001-0.003:0.3-0.4:0.003-0.005:0.001-0.003; The carbon source is one of starch, cellulose, molasses, sodium acetate, mannitol, sucrose, maltose, xylose, and lactose. The nitrogen source is one of the following: peptone, beef extract, yeast powder, soybean meal, NH4Cl4, potassium nitrate, ammonium nitrate, or glutamic acid.

[0019] Furthermore, in S2, the leaching culture temperature conditions are 15-45℃, and the time conditions are 3-12 days.

[0020] The beneficial effects achieved by this invention are: (1) This invention utilizes Klebsiella pneumoniae ( Klebsiella variicola The deep interaction between iron-reducing bacteria and minerals, using the metabolic products of iron-reducing bacteria to dissolve iron minerals, destroys the mineral lattice, thereby dissolving impurity components, provides a new idea for promoting the iron removal and whitening of kaolin towards a green, low-carbon, and efficient direction.

[0021] (2) The present invention contains Klebsiella heterotrophus ( Klebsiella variicola It has a significant iron removal effect, achieving a removal rate of over 90% for iron in iron-rich kaolin. Attached Figure Description

[0022] Figure 1 This is the phylogenetic tree of Klebsiella variicola ZF-01, which is the present invention. Figure 2 This is a colony morphology diagram of Klebsiella variicola ZF-01, the strain of this invention. Figure 3 This is a process flow diagram of a bioleaching method for removing iron from iron-rich kaolin. Detailed Implementation

[0023] The present invention will be further illustrated by the following examples. The preferred examples described herein are for illustrative and explanatory purposes only. The technical means used in the examples are known to those skilled in the art, and the instruments and reagents used are commercially available.

[0024] The first thing this invention aims to protect is a strain of Klebsiella variicola ZF-01, which is deposited at the Guangdong Provincial Center for Microbial Culture Collection, located at 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, on July 28, 2025, with accession number GDMCC No. 66771.

[0025] The *Klebsiella pneumoniae* ZF-01 strain of this invention was initially isolated from raw ore samples collected from the Shange mining area in Shange Town, Maoming City, Guangdong Province. The colony morphology of the *Klebsiella pneumoniae* ZF-01 strain is as follows: Figure 1 As shown. By Figure 1 It can be seen that the colonies of the Klebsiella pneumoniae ZF-01 are round, raised, smooth, with neat edges, and milky white.

[0026] The 16S rDNA sequence of *Klebsiella pneumoniae* ZF-01 was compared with sequences in the GenBank database using BLAST analysis. A phylogenetic tree of *Klebsiella pneumoniae* ZF-01 was constructed, as shown below. Figure 2 As shown. Based on phylogenetic tree analysis, morphological analysis, and the physiological and biochemical characteristics of this strain, strain ZF-01 was identified as *Klebsiella variicola*. It should be noted that the screening, isolation, culture and identification of Klebsiella pneumoniae ZF-01 in this invention are all existing technologies, and will not be described in detail in this invention.

[0027] The second aspect of this invention is the application of Klebsiella pneumoniae ZF-01, specifically its application in removing iron from iron-rich kaolin. The iron-rich kaolin described in this invention typically contains 0.8-12% Fe2O3.

[0028] The above application specifically includes the following steps: S1. Preparation of Klebsiella pneumoniae ZF-01 bacterial suspension: Klebsiella pneumoniae ZF-01 is cultured in a culture medium to obtain fermentation broth; This invention does not have any special limitations on the type of culture medium, as long as it can enable Klebsiella heterotrophus ZF-01 to grow normally.

[0029] In this invention, the culture medium is preferably TSB medium, LB medium, liquid fermentation medium, aniline blue medium, phosphorus-solubilizing fermentation medium, or lignin enrichment medium, more preferably LB medium. In this invention, the pH value of the culture medium is preferably 4–10, more preferably 5–9, and even more preferably 5.

[0030] In this invention, if the culture medium is LB medium, the culture medium preferably also includes a carbon source with a mass percentage of 0.1% and a nitrogen source with a mass percentage of 0.01%.

[0031] In this invention, the carbon source preferably includes one or more of starch, cellulose, molasses, grape pomace, sodium acetate, mannitol, sucrose, maltose, xylose, and lactose, more preferably starch; the nitrogen source preferably includes one or more of peptone, beef extract, yeast powder, soybean meal, NH4Cl4, potassium nitrate, ammonium nitrate, and glutamic acid, more preferably peptone. The culture temperature is preferably 15℃~45℃, more preferably 30℃~36℃, and even more preferably 34℃; the culture time is preferably 2-7 days, and even more preferably 3 days; the liquid volume during the culture is preferably 50-150mL, more preferably 50-100mL, and even more preferably 50mL. In this invention, the culture is preferably carried out in a shaker, and the rotation speed of the shaker is preferably 150-200rpm, and even more preferably 180rpm.

[0032] S2. After mixing iron-rich kaolin, bacterial suspension, water, carbon source, and nitrogen source, the mixture is cultured to remove iron from the iron-rich kaolin.

[0033] Specifically, by mass ratio, the ratio of iron-rich kaolin: bacterial suspension: water: carbon source: nitrogen source is 1:0.001-0.003:0.3-0.4:0.003-0.005:0.001-0.003.

[0034] The carbon source is one of starch, cellulose, molasses, sodium acetate, mannitol, sucrose, maltose, xylose, and lactose. The nitrogen source is one of the following: peptone, beef extract, yeast powder, soybean meal, NH4Cl4, potassium nitrate, ammonium nitrate, or glutamic acid.

[0035] The incubation temperature is 15-45℃, and the incubation time is 3-12 days.

[0036] During the iron reduction process, sugars and amino acids produced by the fermentation of Klebsiella pneumoniae ZF-01 can reduce the iron content in iron-rich kaolin. 3+ Reduced to Fe 2+The soluble complex is formed and then removed. Testing showed that the *Klebsiella pneumoniae* ZF-01 of this invention achieved a removal rate of up to 96.32% for iron in iron-rich kaolin.

[0037] <Example 1> The application of Klebsiella pneumoniae ZF-01 in removing iron from iron-rich kaolin clay includes the following methods: S1. Prepare a suspension of Klebsiella pneumoniae ZF-01; S2. Weigh 1 kg of iron-rich kaolin, 300 g of water, 2 g of bacterial suspension, 5 g of starch, and 3 g of peptone. Mix and culture the microbial slurry at 34°C for 9 days.

[0038] The whiteness and Fe2O3 content of the microbial slurry were tested on days 0, 3, 6 and 9, and the results are shown in Table 1.

[0039] Table 1

[0040] As shown in Table 1, on the 9th day, the iron removal rate in the microbial slurry reached 96.22%, the Fe2O3 content decreased from 10.59% to 0.40%, and the burnt white content increased from 20.7% to 90.0%.

[0041] <Example 2> The application of Klebsiella pneumoniae ZF-01 in removing iron from iron-rich kaolin clay includes the following methods: S1. Prepare a suspension of Klebsiella pneumoniae ZF-01; S2. Weigh 1 kg of iron-rich kaolin, 300 g of water, 2 g of bacterial suspension, 4 g of starch, and 2 g of peptone. Mix and culture the microbial slurry at 34°C for 12 days.

[0042] The microbial slurry was cultured at 34℃ for 12 days.

[0043] The whiteness and Fe2O3 content of the microbial slurry were tested on days 0, 3, 6, 9 and 12, and the results are shown in Table 2.

[0044] Table 2

[0045] Table 2 shows that on day 9, the iron removal rate in the microbial slurry reached 95.37%, the Fe2O3 content decreased from 10.59% to 0.49%, and the whiteness increased from 20.7% to 87.6%. On day 12, the iron removal rate in the microbial slurry reached 96.32%, the Fe2O3 content decreased from 10.59% to 0.39%, and the whiteness increased from 20.7% to 9.2%. This indicates that leaching iron removal from iron-rich kaolin using Klebsiella pneumoniae ZF-01 can significantly improve the utilization value of this low-grade kaolin resource.

[0046] <Example 3> The application of Klebsiella pneumoniae ZF-01 in removing iron from iron-rich kaolin clay includes the following methods: S1. Prepare a suspension of Klebsiella pneumoniae ZF-01; S2. Weigh 10kg of iron-rich kaolin, 3500g of water, 22g of bacterial suspension, 50g of starch, and 25g of peptone. Mix and culture the microbial slurry at 34℃ for 12 days.

[0047] The whiteness and Fe2O3 content of the microbial slurry were tested on days 0, 3, 6, 9 and 12, and the results are shown in Table 3.

[0048] Table 3

[0049] As shown in Table 3, with the increase of leaching time, the iron removal rate in the microbial slurry reached 95.09% on the 12th day, the Fe2O3 content decreased from 8.75% to 0.43%, and the burnt white content increased from 25.9% to 89.4%.

[0050] like Figure 3 As shown, the third aspect of this invention to be protected is a method for removing iron from iron-rich kaolin through bioleaching, specifically including the following steps: S1. Prepare a suspension of Klebsiella pneumoniae ZF-01; S2. Mix iron-rich kaolin, bacterial suspension, water, carbon source, and nitrogen source, and incubate for a period of time to complete the leaching reaction.

[0051] Specifically, by mass ratio, the ratio of iron-rich kaolin: bacterial suspension: water: carbon source: nitrogen source is 1:0.001-0.003:0.3-0.4:0.003-0.005:0.001-0.003.

[0052] The carbon source is one of starch, cellulose, molasses, sodium acetate, mannitol, sucrose, maltose, xylose, and lactose. The nitrogen source is one of the following: peptone, beef extract, yeast powder, soybean meal, NH4Cl4, potassium nitrate, ammonium nitrate, or glutamic acid.

[0053] The leaching culture temperature is 15-45℃, and the culture time is 3-12 days.

[0054] S3. After the leaching reaction is complete, the raw kaolin ore slurry is taken out and screened to remove coarse sand, thus obtaining kaolin coarse concentrate slurry. S4. After classifying and dewatering the kaolin coarse concentrate slurry, iron-removed kaolin is obtained. Specifically, during the classification process, the concentration of the kaolin coarse concentrate slurry is 15-20%.

[0055] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A strain of Klebsiella heterotropha ( Klebsiella variicola ZF-01, characterized in that, Klebsiella pneumoniae ZF-01 is deposited at the Guangdong Provincial Center for Microbial Culture Collection, located at 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, on July 28, 2025, with accession number GDMCC No. 66771.

2. The application of the strain described in claim 1 in removing iron from iron-rich kaolin.

3. The application according to claim 2, characterized in that, Specifically, the following steps are included: S1. Prepare a suspension of Klebsiella pneumoniae ZF-01; S2. After mixing iron-rich kaolin, bacterial suspension, water, carbon source, and nitrogen source, leach and culture the mixture to remove iron from the iron-rich kaolin.

4. The application according to claim 3, characterized in that, Based on the mass ratio, the ratio of iron-rich kaolin: bacterial suspension: water: carbon source: nitrogen source = 1:0.001-0.003:0.3-0.4:0.003-0.005:0.001-0.003; The carbon source is one of starch, cellulose, molasses, sodium acetate, mannitol, sucrose, maltose, xylose, and lactose. The nitrogen source is one of the following: peptone, beef extract, yeast powder, soybean meal, NH4Cl4, potassium nitrate, ammonium nitrate, or glutamic acid.

5. The application according to claim 3, characterized in that, The leaching culture conditions are 15-45℃ and 3-12 days.

6. A method for removing iron from iron-rich kaolin through biological leaching, characterized in that, Specifically, the following steps are included: S1. Prepare a bacterial suspension of Klebsiella pneumoniae ZF-01 as described in claim 1; S2. After mixing iron-rich kaolin, bacterial suspension, water, carbon source, and nitrogen source, the mixture is cultured for a period of time to complete the leaching reaction. S3. After the leaching reaction is complete, the raw kaolin ore slurry is taken out, screened, and then the kaolin coarse concentrate slurry is obtained. The kaolin coarse concentrate slurry is then classified and dewatered in sequence to obtain iron-removed kaolin.

7. The method for removing iron from iron-rich kaolin through bioleaching according to claim 6, characterized in that, In S2, the mass ratio of iron-rich kaolin: bacterial suspension: water: carbon source: nitrogen source is 1:0.001-0.003:0.3-0.4:0.003-0.005:0.001-0.

003.

8. The method for removing iron from iron-rich kaolin through bioleaching according to claim 7, characterized in that, The carbon source is one of starch, cellulose, molasses, sodium acetate, mannitol, sucrose, maltose, xylose, and lactose. The nitrogen source is one of the following: peptone, beef extract, yeast powder, soybean meal, NH4Cl4, potassium nitrate, ammonium nitrate, and glutamic acid.

9. The method for removing iron from iron-rich kaolin through bioleaching according to claim 6, characterized in that, In S2, the leaching culture temperature conditions are 15-45℃, and the time conditions are 3-12 days.

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