A powdery binder for cold-pressed pellets of phosphate rock powder

Abstract

The present invention discloses a powdered binder for cold-pressing phosphate rock pellets. A preparation method for the powdered binder is provided, comprising a raw material formula comprising a thickener, a curing agent, and a heat-resistant agent. The thickener comprises water-based polyurethane powder and acetylated phosphate polysaccharide latex; the curing agent comprises grafted modified polyvinyl acetate, silica sol, silicon phosphate, an inorganic gelling cross-linking material (MO), and a cross-linking agent (YN); and the heat-resistant agent comprises a natural plant extract, titanium dioxide, and boron mud. Because the powdered binder for cold-pressing phosphate rock pellets is a composite of organic and inorganic materials, containing a high-bonding component, a component that cures quickly at room temperature, and a component that is resistant to medium and high temperatures, a small amount of binder can provide high bonding strength at room temperature to bond phosphate rock powder together, thereby improving the pelletization rate and strength, reducing the space or time required for drying, reducing the pulverization rate at medium and high temperatures, and reducing production energy consumption.

Description

Technical Field

[0001] The invention belongs to the technical field of binders for phosphate rock pellets, and particularly relates to a powdery binder for cold-pressed phosphate rock pellets. Background Art

[0002] Phosphate rock powder is a large amount of fine ore produced during the mining or crushing of phosphate rock, containing a certain grade of phosphorus. Thermal yellow phosphorus production primarily uses lump phosphate rock. However, due to its fine particle size, phosphate rock powder cannot be directly used in electric furnaces to produce yellow phosphorus. With the dwindling availability of rich phosphate rock resources and rising prices, the availability of lump phosphate rock suitable for yellow phosphorus production is decreasing, and the use of phosphate rock powder is gaining increasing attention. To efficiently utilize phosphate rock powder, it can be pelletized for use in yellow phosphorus production. Currently, manufacturers commonly add a suitable binder to cold-press phosphate rock into pellets of sufficient strength before using them in electric furnaces for phosphorus production. This involves mixing the phosphate rock powder with an appropriate amount of binder, adding an appropriate amount of water, and then pressing the pellets through a cold press. The pellets are then air-dried to produce the finished product. These pellets have a uniform particle size, high grade, and stability, making them suitable for direct use in electric furnaces to produce yellow phosphorus.

[0003] Binders in the prior art, such as kaolin and bentonite, are relatively low in cost, but have low bonding strength, resulting in low pelletizing efficiency and strength. Large amounts of these binders introduce harmful impurities, which increase power consumption in yellow phosphorus production and reduce pellet quality. Liquid water glass, molasses, and waste paper slurry are prone to uneven mixing with phosphate rock powder, making loading and unloading inconvenient and increasing production costs. Organic binders such as sodium carboxymethyl cellulose, sodium carboxymethyl starch, and sodium polyacrylate are relatively low in cost, have low strength at medium temperatures under the high temperature of an electric furnace, and are easily pulverized. Large amounts of these binders slow down curing and require long pellet drying times, increasing production costs. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a powdered binder for cold-pressing phosphate rock pellets, which has the advantages of improved pelletizing rate, increased strength and no drying required.

[0005] To achieve the above object, the present invention provides the following technical solution: a powdered binder for cold-pressing phosphate rock pellets, and a method for preparing the powdered binder, comprising the following steps:

[0006] S1: Raw material formula composition: 10% to 20% thickener, 55% to 75% curing agent and 15% to 30% heat-resistant agent, the thickener includes water-based polyurethane powder and acetylated phosphate polysaccharide latex, the curing agent includes grafted modified polyvinyl acetate, silica sol, silicon phosphate, inorganic gelling cross-linking material (MO) and cross-linking agent (YN), the heat-resistant agent includes natural plant transformation extract, titanium dioxide and boron mud;

[0007] S2: Waterborne polyurethane powder preparation method: Add 0.1% anti-caking agent (titanium dioxide can be used as an anti-caking agent to prevent the waterborne polyurethane from agglomerating after drying. At the same time, titanium dioxide can combine with boric acid in boron mud to improve thermal strength when in contact with water) to the waterborne polyurethane emulsion prepared in S1, and spray powder in a vacuum spray chamber at a negative pressure of 20-80 kPa;

[0008] S3: Inorganic gelling cross-linking material MO: recycled magnesium construction waste sound insulation materials and fireproof boards, crushed, kiln fired, impurity separation (reagent separation phase, centrifugal separation), supplemented with active cross-linking group materials, and granulated to produce MO;

[0009] S4: Cross-linking agent (YN): Nanyang alkali stone is ground and powdered, and the material addition ratio is strictly controlled to supplement the relevant ingredients. At the same time, active initiators, inhibitors, and lattice retainers are added to compound to form YN;

[0010] S5: Natural plant transformation extract: A gray-black powder formed by fermenting, anaerobic retting, reagent treatment, steam heating, drying and granulation of straw, rice husk, bran and peanut shell biomass.

[0011] Preferably, in said S1, the adhesive has the characteristics of small addition amount, strong bonding force, fast curing speed and resistance to medium and high temperatures. When used in phosphate rock powder, the wet ball drop strength of the prepared pellets is increased, and the compressive strength of the dry ball after drying at room temperature for 2 to 3 days can meet the strength requirements for transportation and use. It also has good hot performance and compressive strength when added to an electric furnace (submersible arc furnace) for smelting.

[0012] Preferably, in S2, the thickener is composed of water-based polyurethane powder and acetylated phosphate polysaccharide latex, and the hydrophilic polar groups (-NH, -OH, -COOH, etc.) of the water-based polyurethane powder and acetylated phosphate polysaccharide latex are combined with phosphate rock powder (Ca 10 The polar group (F - ) forms a certain bond energy after forming a hydrogen bond-like combination, and the covalent bond and van der Waals force cause cross-linking between the adhesive molecules, which bonds the phosphate rock particles together, increases the pellet forming rate, improves the wet ball drop strength, and ensures a higher dry ball strength.

[0013] Preferably, in S3 and S4, the curing agent includes grafted modified polyvinyl acetate, silica sol, silicon phosphate, inorganic gelling cross-linking material (MO) and cross-linking agent (YN). The grafted modified polyvinyl acetate and silica sol are combined, and through the grafted specific functional groups, a binding system (its schematic structural formula is Si-OC=O) can be formed at the end group and the silicon-oxygen bond to provide bonding force under the action of nucleophilic force and electrostatic attraction. At the same time, silicon phosphate can accelerate the solidification and condensation speed of silica sol, increase the pellet forming rate, improve the wet ball drop strength, and ensure a higher dry ball strength; the inorganic gelling cross-linking material (MO) has appropriate activity. After mixing with the cross-linking agent (YN), it can form a combination (the combination is MO·YN·H2O system) under the action of water, and release heat at the same time, which can make the pellets cure quickly during the drying process. The meshing force after drying and curing makes the pellets have a certain dry ball strength during drying.

[0014] Preferably, in S1 and S5, the natural plant transformation extract reacts with the phosphate in the phosphate rock at high temperature to form a high-temperature carbon bridge, and an OPOCO chain appears. In the presence of a silicate system formed by the grafted modified polyvinyl acetate, silica sol and silicon phosphate, medium- and high-temperature liquid phase bonding occurs. In addition, due to the effect of boron in the boron mud, a complex interwoven network lattice (whose schematic structural formula is C-Si-OPOCOBO) is formed in the appropriate liquid phase eutectic system. At the same time, the combination formed by the grafted modified polyvinyl acetate and silica sol (whose schematic structural formula is Si-OC=O) and the combination formed by the inorganic gelled cross-linking material (the combination is MO·YN·H2O system) also have thermal strength at different temperatures, forming a reasonable thermal intensity distribution in each temperature section, so that the pellets have a certain thermal stability when put into the furnace; at the same time, titanium dioxide can combine with boric acid and phosphate rock in the boron mud when in contact with water to improve the thermal stability of the pellets when put into the furnace.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. The powdered adhesive for cold-pressed phosphate rock pellets provided is a composite of organic and inorganic materials, containing high-adhesive components, fast-curing components at room temperature, and medium- and high-temperature resistant components. A small amount of adhesive can provide high adhesion at room temperature to bond the phosphate rock powder together, thereby improving the pelletizing rate, increasing the strength, reducing the drying space or time, reducing the pulverization rate at medium and high temperatures, and reducing the company's production energy consumption; and the adhesive is a fluid powder, which is easy to mix evenly with the phosphate rock powder, convenient to operate, and reduces the company's production costs.

[0017] 2. Since the binder is in powder form, it is easy to mix evenly with phosphate rock powder, making loading and unloading operations convenient, requiring less addition and introducing less harmful impurities, thereby reducing electricity consumption in yellow phosphorus production. It has strong bonding strength and high pellet strength, which reduces the return rate and energy consumption of the enterprise. It has a fast curing speed and is suitable for enterprises that do not have drying equipment, hot pressing equipment, or insufficient drying space, thereby reducing energy consumption. It is resistant to medium and high temperatures, reducing the impact of pellet breakage on the normal phosphorus production reaction in the electric furnace.

[0018] 3. A powdered adhesive composited with organic and inorganic materials. The adhesive contains high-bonding components, components that quickly solidify at room temperature, and components that are resistant to medium and high temperatures. It features low dosage, strong adhesion, fast curing, and resistance to medium and high temperatures. This powdered adhesive mixes easily with phosphate rock powder and facilitates loading and unloading. The cross-linking effect of the adhesive molecules upon contact with water provides high adhesion, tightly bonding the phosphate rock particles together, giving the pellets high wet-bulb drop strength and dry-bulb compressive strength. The intermolecular bonds provide meshing force, giving the pellets a certain dry-bulb strength and thermal stability during drying. This can reduce the impact of pellet breakage on the normal phosphorus production reaction in electric furnaces and can be used by companies without drying equipment, hot pressing equipment, or insufficient drying space. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with examples of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0020] The present invention provides a technical solution: a powdered binder for cold-pressing phosphate rock pellets. A method for preparing the powdered binder is provided, comprising the following steps:

[0021] Thickener: water-based polyurethane powder, acetylated phosphate polysaccharide latex.

[0022] Curing agent: grafted modified polyvinyl acetate, silica sol, silicon phosphate, inorganic gelling cross-linking material (MO), cross-linking agent (YN).

[0023] Heat-resistant agents: natural plant transformation extracts, titanium dioxide, boron mud.

[0024] Combination 1: thickener 10%, curing agent 75%, heat resistance agent 15%, i.e. water-based polyurethane powder 3%, acetylated phosphate polysaccharide latex 7%, grafted modified polyvinyl acetate 16%, silica sol 12%, silicon phosphate 7%, inorganic gelling cross-linking material (MO) 33%, cross-linking agent (YN) 7%, natural plant transformation extract 7%, titanium dioxide 1%, and boron mud 7%.

[0025] Combination 2: thickener 20%, curing agent 55%, temperature resistance agent 25%, i.e. water-based polyurethane powder 6%, acetylated phosphate polysaccharide latex 14%, grafted modified polyvinyl acetate 13%, silica sol 10%, silicon phosphate 7%, inorganic gelling cross-linking material (MO) 20%, cross-linking agent (YN) 5%, natural plant transformation extract 12%, titanium dioxide 1%, and boron mud 12%.

[0026] Combination three: thickener 15%, curing agent 64%, temperature resistance agent 21%, i.e. water-based polyurethane powder 5%, acetylated phosphate polysaccharide latex 10%, grafted modified polyvinyl acetate 4%, silica sol 3%, silicon phosphate 2%, inorganic gelling cross-linking material (MO) 45%, cross-linking agent (YN) 10%, natural plant transformation extract 10%, titanium dioxide 1%, and boron mud 10%.

[0027] Comparison of the strength of pellets pressed with this phosphate rock binder and ordinary binders:

[0028]

[0029] Comparison of the phosphate rock binder with ordinary binders

[0030] When the binder is added in an amount of 3% to 4%, the wet ball can achieve a drop strength of 1.5 meters and remain intact after more than two drops. The compressive strength after two days of drying is more than 800N, and the compressive strength after three days of drying is more than 1200N. The compressive strength of the pellets measured after being fired at 500°C for one hour is more than 1000N, and the compressive strength of the pellets measured after being fired at 800°C for one hour is more than 800N. The pellets have uniform particle size, high grade and stability, which can increase the permeability of the material layer and reduce energy consumption.

[0031] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A powdery binder for cold-pressing phosphate rock pellets, and a method for preparing the powdery binder, are provided, characterized in that: The following steps are involved: S1: Raw material formula composition: thickener 10% to 20%, curing agent 55% to 75% and heat-resistant agent 15% to 30%, the thickener includes water-based polyurethane powder and acetylated phosphate polysaccharide latex, the curing agent includes grafted modified polyvinyl acetate, silica sol, silicon phosphate, inorganic gelling cross-linking material MO and cross-linking agent YN, the heat-resistant agent includes natural plant transformation extract, titanium dioxide and boron mud; S2: Waterborne polyurethane powder preparation method: add 0.1% anti-caking agent to the waterborne polyurethane emulsion prepared in S1, and spray powder in a vacuum spray chamber with a negative pressure of 20~80kPa; S3: Inorganic gelling cross-linking material MO: recycled magnesium construction waste sound insulation materials and fireproof boards, crushed, kiln fired, impurity separated, supplemented with active cross-linking group materials, and granulated into MO; S4: Cross-linking agent YN: Nanyang alkali stone is ground and powdered, and the material addition ratio is strictly controlled to supplement the relevant ingredients. At the same time, active initiators, inhibitors and lattice retainers are added to compound YN; S5: Natural plant transformation extract: A gray-black powder formed by fermenting, anaerobic retting, reagent treatment, steam heating, drying and granulation of straw, rice husk, bran and peanut shell biomass.

Images