CN105331808A - Method for iron ore powder agglomeration - Google Patents

Abstract

The invention discloses a method for iron ore powder agglomeration. The method aims at improving the iron grade of iron ore, reducing energy consumption and reducing environmental pollution. The method includes the steps that iron ore powder, limestone powder, magnesium cement and pore-forming agents are proportioned for iron ore powder briquettes; primary mixing is carried out, and the small-granularity iron ore powder, the limestone powder, the magnesium cement and the pore-forming agents are put in a mixer; secondary mixing is carried out, the primary mixture and the remaining large-granularity iron ore powder are put into the mixer to be mixed evenly to obtain a uniform mixture; the uniform mixture is placed in a cuboid-shaped mold to be pressed into an iron briquette raw material; the iron briquette raw material is roasted; and crushing and screening are carried out. According to the method, the magnesium cement serves as a binder and a MgO additive, the pore-forming agents are added to the mixture, the cold press molding technology is adopted for pressing multi-pore iron briquettes, and therefore the iron ore powder agglomeration efficiency is improved, the metallurgical performance of the iron briquettes is improved, the production technology process is simplified, the quantity of the binder used in sintering and palletizing is reduced, iron ore resources are expanded, and the bulk density of the iron briquettes and the production efficiency of a blast furnace are improved.

Description

A kind of method of iron ore powder agglomeration

technical field

The invention relates to a method for preparing blast furnace raw materials, in particular to a method for making iron ore powder into agglomerates.

Background technique

Fine ore agglomeration is to make ore blocks that meet the smelting requirements by artificial means after batching metal ore powder that cannot be directly put into the furnace. Powder ore agglomeration is an important part of raw material preparation before smelting. It not only expands the source of smelting raw materials, but also improves the quality of raw materials.

The main methods of iron ore powder agglomeration are sintering and pelletizing. Sintering is to mix fine-grained iron-containing raw materials with fuel and flux in a certain proportion, add water to moisten and mix them evenly, and then spread them on the sintering machine. After igniting, ventilating, and burning the fuel in the sintering material to generate high temperature, a series of The physical and chemical reactions of the iron ore minerals produce some low melting point substances, forming a certain amount of liquid phase, which wets and bonds the iron ore particles, and forms a porous block product with a certain strength after cooling - sinter. Pelletizing: Firstly, powder ore is added with appropriate amount of water and binder to make green balls with uniform viscosity and sufficient strength. After drying and preheating, they are roasted in an oxidizing atmosphere to make the green balls agglomerate and make pellets.

The pellet production process usually can only process finer-grained and high-grade iron ore concentrates, and the binder bentonite needs to be added in the pelletizing process, which will reduce the pellet grade and increase the amount of blast furnace slag, and the use of pellets in the blast furnace requires 1250 High-temperature oxidation roasting above ℃ consumes a lot of energy and emits a lot of carbon dioxide. At the same time, the pellet structure is relatively dense, and its reducibility is lower than that of porous sinter. Although the sintering process can handle iron ore powders of various sizes, the sintering yield is relatively Low (only about 70%), low energy utilization rate (the sintering machine has about 50% air leakage rate), and sintering coke powder or coal powder produces a large amount of sulfide and nitride, polluting the atmospheric environment. At present, the addition of magnesia-containing substances in sintered pellets does not play a role in bonding, but only plays a role in adjusting the metallurgical properties of sintered pellets. Its addition increases the amount of binder used in sintered pellets, reduces the iron grade of sintered pellets, and increases energy. consume.

The patent application publication number CN104232884A discloses a method for making iron ore powder agglomerates. This method can comprehensively utilize resources, expand the types of raw materials for ironmaking, remove harmful impurities, recover beneficial elements, protect the environment, and improve the metallurgical properties of the ore. However, this method still uses a simple traditional sintering trolley process to process metallurgical iron-containing waste to produce sintered ore, which has low production efficiency, low energy utilization, and produces a large amount of sulfide and nitride that pollute the air. The different actual conditions cause its composition to fluctuate greatly, which easily causes the chemical composition of sinter to fluctuate.

Contents of the invention

The invention provides a method for agglomerating iron ore powder, aiming at improving the iron grade of iron ore, saving energy consumption and reducing environmental pollution.

A kind of iron ore powder agglomeration method provided by the invention comprises the following steps:

a. Iron ore powder block ingredients: by weight percentage, iron ore powder 85-90%, limestone powder 5-10%, magnesium cement 3-5%, pore-forming agent 0.5%, the iron ore powder wherein is divided into according to particle size Two parts, one part has a particle size of 0-1mm, and the other has a particle size of 1-5mm;

b. Primary mixing: put iron ore powder with a particle size of 0-1mm, 5-10% limestone powder, 3-5% magnesium cement and 0.5% pore-forming agent in the mixer, and the mixing time is 3-5min. And add water vapor of 2-4% of the total mass of the material during the mixing process to obtain a primary mixture;

c. Secondary mixing: Put the primary mixture and the remaining iron ore powder with a particle size of 1-5mm into the mixer and mix them evenly for 2-3 minutes, and add 3-4% water of the total mass of the materials during the mixing process Steam to obtain a homogeneous mixture;

d. Compression: put the homogeneous mixture into a cuboid-shaped mold and press it into an iron block raw meal;

e. High-pressure roasting: the raw material of the iron block is roasted under the condition of a pressure of 2.0-8.0Mpa and a temperature of 200-400°C, and the roasting time is 15-30min to remove chlorine in the iron block;

f. Crushing and screening: crush and sieve the roasted iron nuggets, return ingredients with a particle size of less than 5mm, 5-20mm is the finished porous iron nugget, the binary alkalinity of the finished porous iron nugget R=1.10-1.50, TFe weight percent The content is 54-63%.

The magnesium cement in the step a is magnesium oxychloride cement with a particle size of ≤200 mesh; the pore-forming agent in the step a is a spherical plastic foam with an average diameter of 0.1-2 mm.

Compared with the prior art of the same kind, the present invention has remarkable beneficial effects embodied in:

Using magnesium cement as binder and MgO additive, adding pore-forming agent to the mixture, adopting cold pressing molding technology, pressing into porous iron blocks, which improves the efficiency of iron ore powder agglomeration, improves the metallurgical properties of iron blocks, and simplifies The production process reduces the use of binders in sintered pellets (quicklime, bentonite), improves the iron grade of iron ore, reduces energy consumption, expands iron ore resources, increases the bulk density of iron lumps and blast furnace production efficiency, and reduces environmental pollution.

detailed description

The present invention is described in more detail below by way of examples.

Example 1

According to the requirements of binary alkalinity R=1.10 and TFe content of 63%, the ingredients are calculated by weight percentage: 89.5% iron ore powder, 5% limestone powder, 5% magnesium cement, spherical plastic foam with an average diameter of 0.1-2mm 0.5% pore-forming agent, divide the iron ore powder into two parts according to the particle size, one part has a particle size of 0-1mm, and the other has a particle size of 1-5mm; put iron ore powder with a particle size of xx-yy, 5 % limestone powder, 5% magnesium cement and 0.5% pore-forming agent were mixed for 3 minutes, and 2% water vapor of the total mass was added during the mixing process to obtain a primary mixture; the primary mixture was mixed with a particle size of 1 The remaining iron ore powder of -5mm is put into the mixer and mixed for 2 minutes, and 4% water vapor of the total mass is added during the mixing process to obtain a uniform mixture; the uniform mixture is put into a cuboid mold for pressing Forming iron block raw meal; the iron block raw meal is roasted for 15 minutes at a pressure of 3.0Mpa and a temperature of 200°C, and the roasted iron block is crushed and screened to obtain a finished porous iron block with a particle size of 5-20mm.

Example 2

According to the requirements of binary alkalinity R=1.50 and TFe content of 55%, the ingredients are calculated by weight percentage: 84.5% iron ore powder, 10% limestone powder, 5% magnesium cement, spherical plastic foam with an average diameter of 0.1-2mm 0.5% pore forming agent, the iron ore powder in it is divided into two parts according to the particle size, one part has a particle size of 0-1mm, and the other has a particle size of 1-5mm; put iron ore powder with a particle size of 0-1mm, 10 % limestone powder, 5% magnesium cement and 0.5% pore-forming agent were mixed for 5 minutes, and 3% water vapor of the total mass was added during the mixing process to obtain a primary mixture; the primary mixture and a particle size of 1 The remaining iron ore powder of -5mm is put into the mixer and mixed for 3 minutes, and 4% water vapor of the total mass is added during the mixing process to obtain a uniform mixture; the uniform mixture is put into a cuboid mold and pressed into Iron block raw meal: The iron block raw meal is roasted for 20 minutes under the conditions of pressure of 4.0Mpa and temperature of 260°C, and the roasted iron block is crushed and screened to obtain a finished product with a particle size of 5-20mm.

Example 3

According to the requirements of binary alkalinity R=1.20 and TFe content of 59%, the ingredients are calculated by weight percentage: 89.5% iron ore powder, 6% limestone powder, 4% magnesium cement, spherical plastic foam with an average diameter of 0.1-2mm 0.5% pore forming agent, the iron ore powder in it is divided into two parts according to the particle size, one part has a particle size of 0-1mm, and the other has a particle size of 1-5mm; put iron ore powder with a particle size of 0-1mm, 6 % limestone powder, 4% magnesium cement and 0.5% pore-forming agent were mixed for 4 minutes, and 3% water vapor of the total mass was added during the mixing process to obtain a primary mixture; the primary mixture and a particle size of 1 The remaining iron ore powder of -5 mm is put into the mixer and mixed for 2 minutes, and 4% water vapor of the total mass is added during the mixing process to obtain a uniform mixture; the uniform mixture is put into a cuboid mold and pressed into Iron block raw meal: The iron block raw meal is roasted for 30 minutes at a pressure of 8.0Mpa and a temperature of 400°C, and the roasted iron block is crushed and screened to obtain a finished product with a particle size of 5-20mm.

Example 4

According to the requirements of binary alkalinity R=1.30 and TFe content of 60%, the ingredients are calculated by weight percentage: 87.5% iron ore powder, 8% limestone powder, 3% magnesium cement, spherical plastic foam with an average diameter of 0.1-2mm 0.5% pore forming agent, the iron ore powder in it is divided into two parts according to the particle size, one part has a particle size of 0-1mm, and the other has a particle size of 1-5mm; put iron ore powder with a particle size of 0-1mm, 8 % limestone powder, 3% magnesium cement and 0.5% pore-forming agent were mixed for 3 minutes, and 2% water vapor of the total mass was added during the mixing process to obtain a primary mixture; the primary mixture and a particle size of 1 The remaining iron ore powder of -5 mm is put into the mixer and mixed for 2 minutes, and 4% water vapor of the total mass is added during the mixing process to obtain a uniform mixture; the uniform mixture is put into a cuboid mold and pressed into Iron block raw meal: The iron block raw meal is roasted for 25 minutes under the conditions of pressure of 6.0Mpa and temperature of 300°C, and the roasted iron block is crushed and screened to obtain a finished product with a particle size of 5-20mm.

Table 1 embodiment effect

Example TFe% Yield% Drum coefficient FeO% Reduction Example 1 63.01 94.67 93.34 2.12 86.34 Example 2 56.23 93.33 90.34 1.34 89.23 Example 3 59.23 90.45 89.34 3.12 84.37 Example 4 60.12 88.67 84.34 4.34 83.56

Claims (2)

1. A method for iron ore powder agglomeration is characterized in that the method may further comprise the steps: a. Iron ore powder block ingredients: by weight percentage, iron ore powder 85-90%, limestone powder 5-10%, magnesium cement 3-5%, pore-forming agent 0.5%, the iron ore powder wherein is divided into according to particle size Two parts, one part has a particle size of 0-1mm, and the other part has a particle size of 1-5mm; b. Primary mixing: put iron ore powder with a particle size of 0-1mm, 5-10% limestone powder, 3-5% magnesium cement and 0.5% pore-forming agent in the mixer, and the mixing time is 3-5min. And add water vapor of 2-4% of the total mass of the material during the mixing process to obtain a primary mixture; c. Secondary mixing: Put the primary mixture and the remaining iron ore powder with a particle size of 1-5mm into the mixer and mix them evenly for 2-3 minutes, and add 3-4% water of the total mass of the materials during the mixing process Steam to obtain a homogeneous mixture; d. Compression: put the homogeneous mixture into a cuboid-shaped mold and press it into an iron block raw meal; e. High-pressure roasting: The raw material of the iron block is roasted under the conditions of a pressure of 2.0-8.0Mpa and a temperature of 200-400°C, and the roasting time is 15-30min to remove chlorine in the iron block; f. Crushing and screening: crush and sieve the roasted iron nuggets, return ingredients with a particle size of less than 5mm, 5-20mm is the finished porous iron nugget, the binary alkalinity of the finished porous iron nugget R=1.10-1.50, TFe weight percent The content is 54-63%. 2. A method for agglomerating iron ore powder according to claim 1, characterized in that the magnesium cement in step a is magnesium oxychloride cement with a particle size≤200 mesh; the pore-forming agent in step a is a spherical plastic Foam, with an average diameter of 0.1-2mm.