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CN-121673433-B - Filter aid for reducing water content of iron ore slurry and preparation method thereof

CN121673433BCN 121673433 BCN121673433 BCN 121673433BCN-121673433-B

Abstract

The invention discloses a filter aid for reducing the water content of iron ore slurry and a preparation method thereof, and belongs to the technical field of filter aids. The filter aid is prepared by taking starch as a matrix and matching with raw materials such as bromoalkane, bromoquaternary ammonium salt and the like through pre-oxidation, alkaline activation and double-bromografting and post-treatment, wherein the bromoalkane is normal monobasic alkyl bromide with a carbon chain length of 8-14, and the bromoquaternary ammonium salt is 2-bromoethyl trimethyl ammonium bromide or 6-bromoethyl trimethyl ammonium bromide. The invention realizes synchronous grafting of the hydrophobic alkyl chain and the cationic quaternary ammonium salt through the covalent bond, not only can damage the hydration film on the surface of the mineral and transform the attached water, but also can flocculate fine particles and impurities, and optimize the pore structure of the filter cake. The filter aid overcomes the defects of single function and poor synergy of the traditional technology, remarkably improves the filtering efficiency, reduces the water content of a filter cake and the turbidity of filtrate, has the advantages of environment-friendly raw materials and simple preparation process, is suitable for industrial production, and is suitable for the solid-liquid separation and filtering scene of the iron ore pulp.

Inventors

  • TIAN FANG

Assignees

  • 鞍山天雨发展有限公司

Dates

Publication Date
20260512
Application Date
20260209

Claims (10)

  1. 1. A filter aid for reducing the water content of iron ore slurry is characterized by comprising, by weight, 100 parts of starch, 12-25 parts of bromoalkane, 8-15 parts of bromoquaternary ammonium salt, 8-12 parts of sodium hydroxide, 950-1050 parts of deionized water and 80-120 parts of ethanol; the bromoalkane is normal monobasic alkyl bromide with the carbon chain length of 8-14 and is selected from one of 1-bromooctane, 1-bromodecane, 1-bromododecane and 1-bromotetradecane; The bromoquaternary ammonium salt is selected from one of 2-bromoethyl trimethyl ammonium bromide or 6-bromohexyl trimethyl ammonium bromide; the preparation method of the filter aid for reducing the water content of the iron ore slurry comprises the following steps: (1) Adding starch and deionized water into a reaction kettle, stirring for 10-30min at normal temperature, then adding ammonium persulfate, keeping stirring and heating to 90-100 ℃, and carrying out heat preservation reaction for 50-70min to obtain pre-oxidized starch paste; (2) After the pre-oxidized starch paste is cooled to 45-55 ℃, adding sodium hydroxide, and stirring for 10-30min at 300-400r/min to obtain sodium starch alkoxide paste; (3) Preparing bromoquaternary ammonium salt into bromoquaternary ammonium salt water solution for standby; (4) Maintaining the temperature of the system at 45-55 ℃, dropwise adding bromoalkane into the system, after the dropwise adding is finished, carrying out heat preservation reaction for 2-4 hours, then dropwise adding a bromoquaternary ammonium salt aqueous solution, and after the dropwise adding is finished, carrying out reaction for 14-18 hours to obtain grafted modified starch paste; (5) After the grafted modified starch paste is cooled to room temperature, regulating the pH value of the system to be neutral by using a dilute hydrochloric acid solution, adding ethanol, stirring for 30-60min, filtering and collecting a filter cake through a plate frame, washing the filter cake with deionized water for 1-2 times, drying the filter cake, and crushing the filter cake to 80-120 meshes to obtain the filter aid for reducing the water content of the iron ore slurry.
  2. 2. The filter aid for reducing the moisture content of iron ore pulp according to claim 1, wherein the starch is selected from one of corn starch, wheat starch, tapioca starch or potato starch.
  3. 3. The method for preparing the filter aid for reducing the moisture content of the iron ore slurry according to any one of claims 1 to 2, comprising the steps of: (1) Adding starch and deionized water into a reaction kettle, stirring for 10-30min at normal temperature, then adding ammonium persulfate, keeping stirring and heating to 90-100 ℃, and carrying out heat preservation reaction for 50-70min to obtain pre-oxidized starch paste; (2) After the pre-oxidized starch paste is cooled to 45-55 ℃, adding sodium hydroxide, and stirring for 10-30min at 300-400r/min to obtain sodium starch alkoxide paste; (3) Preparing bromoquaternary ammonium salt into bromoquaternary ammonium salt water solution for standby; (4) Maintaining the temperature of the system at 45-55 ℃, dropwise adding bromoalkane into the system, after the dropwise adding is finished, carrying out heat preservation reaction for 2-4 hours, then dropwise adding a bromoquaternary ammonium salt aqueous solution, and after the dropwise adding is finished, carrying out reaction for 14-18 hours to obtain grafted modified starch paste; (5) After the grafted modified starch paste is cooled to room temperature, regulating the pH value of the system to be neutral by using a dilute hydrochloric acid solution, adding ethanol, stirring for 30-60min, filtering and collecting a filter cake through a plate frame, washing the filter cake with deionized water for 1-2 times, drying the filter cake, and crushing the filter cake to 80-120 meshes to obtain the filter aid for reducing the water content of the iron ore slurry.
  4. 4. The method for preparing a filter aid for reducing the water content of iron ore slurry according to claim 3, wherein the weight ratio of the starch to the ammonium persulfate in the step (1) is 1:0.0003-0.0006.
  5. 5. The method for preparing a filter aid for reducing a water content of an iron ore slurry according to claim 3, wherein the stirring rate in (1) is 300-400r/min.
  6. 6. The method for preparing a filter aid for reducing the water content of iron ore slurry according to claim 3, wherein the sodium hydroxide in the step (2) is an industrial grade flake alkali with a purity of not less than 96%.
  7. 7. The method for preparing a filter aid for reducing the moisture content of iron ore slurry according to claim 3, wherein the concentration of the aqueous solution of the bromoquaternary ammonium salt in (3) is 30-50wt%.
  8. 8. The method for preparing a filter aid for reducing the water content of iron ore slurry according to claim 3, wherein the dropwise adding time of bromoalkane in the step (4) is 10-20min, and the dropwise adding time of bromoquaternary ammonium salt aqueous solution is 20-40min.
  9. 9. The method for preparing a filter aid for reducing the moisture content of iron ore slurry according to claim 3, wherein the concentration of the dilute hydrochloric acid solution in (5) is 0.1 to 0.5mol/L.
  10. 10. The method for preparing filter aid for reducing water content of iron ore slurry according to claim 3, wherein the drying mode in (5) is one of normal pressure hot air drying, vacuum drying or blade drying, the drying temperature is controlled to be 60-80 ℃, and the water content of the material is less than or equal to 5%.

Description

Filter aid for reducing water content of iron ore slurry and preparation method thereof Technical Field The invention relates to the technical field of filter aids, in particular to a filter aid for reducing the water content of iron ore slurry and a preparation method thereof. Background In the iron ore dressing industry, in order to realize efficient separation of useful minerals and gangue impurities, a combined process of 'stage grinding-magnetic separation-anion reverse flotation' is generally adopted, wherein the fine grinding operation is a key link for improving the dissociation degree of mineral monomers and guaranteeing the subsequent separation precision. As the grade of iron ore resources is gradually reduced, the grinding granularity needs to be further refined in order to reach the grade of concentrate required by smelting, so that the proportion of-200 mesh fine particle fraction in ore pulp is obviously increased, and the specific surface area of particles is greatly increased. Meanwhile, agents such as inhibitors, collectors, sodium silicate (water glass) and the like added in the flotation process can be adsorbed on the surfaces of iron ore particles, so that ore pulp forms a stable colloid system, the thickness of hydration film on the surfaces of the mineral particles is increased and firmer, further the viscosity of the ore pulp is increased, the fluidity of the ore pulp is deteriorated, and a serious challenge is brought to the subsequent solid-liquid separation and filtration. In the current industrial production, the problems of high water content of a filter cake, low water filtering speed, high turbidity of filtrate and the like generally exist in a filtering link, the excessively high water content of the filter cake not only can increase the energy consumption of a subsequent pellet sintering process, but also can cause insufficient pellet strength and poor sintering air permeability to influence smelting efficiency, and impurities such as fine silica mud, organic medicaments and the like remained in the filtrate not only increase water treatment cost, but also have the risk of losing fine iron ore particles, so that resource waste is caused. To improve the iron ore slurry filtration performance, various solutions have been proposed in the prior art. Part of the technologies adopt inorganic-organic compound coagulant compound systems such as polyaluminium chloride (PAC), polyacrylamide (PAM), polyaluminium ferric sulfate (PAFS) and the like, increase the particle size by neutralizing colloid charges of ore pulp and bridging flocculation, reduce the viscosity of the ore pulp so as to improve the filtering efficiency, and the other technologies adopt single cation modified starch as a filter aid, realize flocculation agglomeration of fine particles by utilizing the adsorption neutralization effect of cation groups, and try to treat the starch through hydrophobic modification, so as to enhance the hydrophobicity of the mineral surface to destroy a hydration membrane. The existing schemes can alleviate the problem of pulp filtration to a certain extent, for example, the compound coagulant can effectively reduce the viscosity of pulp, the cationic modified starch can improve the particle agglomeration effect, and the hydrophobic modified starch can reduce the water attached to the surface of minerals. However, the prior art still has the obvious defects that each component in the compound coagulant system is only physically mixed, the chemical bonding effect is lacked, the synergistic stability is poor, the system has no hydrophobic functional group, a hydration film firmly on the surface of minerals cannot be damaged from the root, the removal effect on the attached water is limited, the water content of a filter cake is still difficult to meet the industrial requirement, only particle flocculation can be realized by single cation modified starch, the problem of attached water residue caused by the hydration film cannot be solved, the dehydration depth is insufficient, the hydration film can be damaged by single hydrophobic modified starch, the cation flocculation function is lacked, fine particles are difficult to agglomerate due to electrostatic repulsion, the filter cake is in a compact accumulation state, the filtration resistance is large, the filtration rate is low, in addition, the inorganic salt components contained in part of the compound system possibly influence the subsequent smelting process, and corrosive reagents or refractory components introduced in the preparation process of part of filter aids can bring production safety and environmental protection pressure. Therefore, developing a filter aid which has the functions of efficient hydrophobic membrane rupture and strong flocculation impurity removal, has good synergistic stability and is environment-friendly and safe becomes a key requirement for solving the difficult problem of iron ore pulp filtration and improvin