CN108516689B - A kind of method for preparing microcrystalline foam glass from high silicon iron tailings and blast furnace slag - Google Patents

Abstract

A method for preparing microcrystalline foam glass from high-silicon iron tailings and blast furnace slag comprises the following steps: (1) preparing high-silicon iron tailings, blast furnace slag and clay as raw materials; (2) preparing titanium dioxide, borax, sodium carbonate, calcium carbonate and sodium metaphosphate as additives; (3) mixing all the raw materials and additives, and wet-grinding to prepare slurry; (4) performing spray granulation to prepare powder particles; (5) filling the powder particles into a mould, and then carrying out roasting, foaming and crystallization processes by using a heating furnace; (6) cooling to normal temperature along with the furnace. The method has simple preparation process, uses waste as raw materials, realizes the resource utilization of solid waste, and obtains the microcrystalline foam glass with high product value.

Description

A kind of method for preparing microcrystalline foam glass from high silicon iron tailings and blast furnace slag

technical field

The invention belongs to the technical field of materials, and relates to a method for preparing microcrystalline foam glass from high-silicon iron tailings and blast furnace slag.

Background technique

Foam glass is a kind of porous glass. There are a large number of closed pores in the glass matrix. It has excellent properties such as light weight, heat insulation, fire resistance, sound absorption and corrosion resistance. It is a green and environmentally friendly material; traditional foam glass preparation is It is prepared from a certain amount of broken glass, foaming agent, foam stabilizer and modified additives, etc., after being finely ground and mixed, and then placed in a mold through preheating, melting, foaming, annealing and other technological processes; The pore size of the pores is between 1 and 4 mm, and the porosity is greater than 60%. The volume density of the foamed glass with better performance is between 0.2 and 0.6 g/cm ³ , the compressive strength is between 1 and 1.7 MPa, and the thermal conductivity is lower than 0.35. W/(m*K); glass-ceramic, also known as glass-ceramic, is a kind of micro-crystal obtained by controlling crystallization under specific conditions to generate a large number of micro-crystal phases in the glass phase during the heating process of the base glass. Solid material with coexistence of glass phase and vitreous phase; high silicon iron tailings and blast furnace slag are used to prepare foam glass, because some metal oxides in both can act as nucleating agents to induce crystallization, as well as interface-induced crystallization during foaming , and control the temperature conditions during sintering, so that the amount of microcrystalline phase is generated in the foam glass product, and the microcrystalline foam glass is obtained; compared with the amorphous foam glass product, the microcrystalline foam glass has higher strength and better Heat insulation and stability; the traditional preparation process of foamed glass-ceramic is generally divided into two steps. After the raw materials are crushed, they are mixed with additives, and are subjected to secondary roasting at high temperature to achieve foaming and crystallization. The process is cumbersome and complex, and the energy consumption is high.

High-silicon iron tailings and blast furnace slag are both bulk solid wastes discharged by the iron and steel industry; blast furnace slag is formed from gangue in ore, ash in fuel and non-volatile components in limestone flux during blast furnace ironmaking. Solid waste residue is one of the waste residues with the largest output in the metallurgical industry. At present, the utilization rate of blast furnace slag in China is about 85%. The main application and production are low value-added products such as cement and concrete. The solid waste discharged later, the high silicon iron tailings are characterized by the content of _SiO2 in the composition exceeding 70%, the mineral composition is quartz minerals and iron-bearing minerals, the particle size is less than 0.124mm, and has a high melting point; China's iron ore The grade is low, the tailings output is large, and the comprehensive utilization rate is less than 10%. The accumulation of a large number of iron tailings not only pollutes the soil and groundwater, and the floating dust enters the atmosphere and harms human health, but also occupies a lot of land resources. The tailings dam has potential safety hazards. .

SUMMARY OF THE INVENTION

The object of the present invention is to provide a method for preparing microcrystalline foam glass from high-silicon ferrous tailings and blast furnace slag. and additives such as sodium metaphosphate. Compared with the traditional preparation method, this method only needs one roasting in a medium temperature furnace to realize foaming and crystallization of the glass phase, and realize the resource utilization of high-silicon iron tailings and blast furnace slag. Microcrystalline foam glass with coexisting crystallite phases.

The method of the present invention comprises the following steps:

1. Prepare high-silicon ferrous tailings, blast furnace slag and clay as raw materials. According to the mass percentage of the raw materials, high-silicon ferrous tailings account for 40-50%, blast furnace slag accounts for 35-44%, and clay accounts for 11-19%;

2. Prepare titanium dioxide, borax, sodium carbonate, calcium carbonate and sodium metaphosphate as additives; in the additives, titanium dioxide accounts for 1-3% of the total mass of all raw materials, borax accounts for 2-4% of the total mass of all raw materials, and sodium carbonate accounts for 2-7% of the total mass of all raw materials, calcium carbonate accounts for 1-6% of the total mass of all raw materials, and sodium metaphosphate accounts for 0.5-1.5% of the total mass of all raw materials;

3. Mix all the raw materials and additives to form a mixed material, then wet-grind with a ball mill, mix evenly and make a slurry; the weight percentage of water in the slurry is 30-40%;

4. Inject the slurry into the spray granulator for spray granulation to make powder particles;

5. Fill the powder particles into the mold, and then place them in the heating furnace to carry out the process of baking foaming and crystallization; the temperature system in the process of baking foaming and crystallization is: the furnace temperature is The rate of min is raised to 850-980°C, and the temperature is kept for at least 20 minutes, and then the temperature is raised to 1100-1200°C at a heating rate of 3-5°C/min, and the temperature is kept for 60-100 minutes;

6. After the roasting, foaming and crystallization process is completed, it is cooled to normal temperature with the furnace to obtain microcrystalline foam glass.

The above-mentioned high-silicon iron tailings contain 81-82% of SiO ₂ , 0.6-0.7% of Al ₂ O ₃ , 14-15% of Fe ₂ O ₃ , 0.4-0.5% of CaO, and 0.3-0.4% of Na ₂ O 3 by mass percentage. , TiO ₂ 0.05-0.1%, MgO 0.7-0.8%, K ₂ O 0.1-0.2%, and the rest are impurities.

The above-mentioned blast furnace slag contains 31-32% of SiO ₂ , 15-16% of Al ₂ O ₃ , 0.5-0.8% of Fe ₂ O ₃ , 43-44% of CaO, 0.4-0.5% of Na ₂ O , 0.5-0.5% of TiO ₂ by mass percentage. 0.6%, MgO 0.3-0.4%, K ₂ O 0.2-0.3%, and the rest are impurities.

The bulk density of the above-mentioned microcrystalline foam glass is 0.45-0.67 g/cm ³ , the compressive strength is 2.0-4.5 MPa, and the thermal conductivity is 0.15-0.3 W/(m·K).

In the above method, the mass ratio of water, mixed material and grinding ball during wet grinding is 0.5:1:4.

The content of SiO ₂ and Fe ₂ O ₃ in high-silicon ferrous tailings is higher, the quartz minerals are more and the melting point is higher, while the content of CaO in blast furnace slag is higher. According to the ternary phase diagram of SiO ₂ -CaO-Fe ₂ O ₃ , The eutectic composition ratio of the three components is found, and the calculation shows that by doping high-silicon ferrous tailings and blast furnace slag with each other, the raw materials can be eutectic at a lower temperature, and titanium dioxide is added to provide TiO ₂ as an inducer Crystal nuclei for crystallization, thereby achieving the conditions for preparing microcrystalline foam glass; the powder batch obtained by the method of the present invention can be filled with closed pores after only one roasting, with low bulk density, high strength and thermal insulation performance. Good high-performance microcrystalline foam glass; the method of the invention provides a new idea for the utilization of two kinds of industrial waste residues.

The method of the present invention has the following advantages: 1) the preparation process is simple, and there is no complicated operation process; 2) the raw materials used are high-silicon iron tailings and blast furnace slag iron and steel industry solid waste, which realizes the resource utilization of the solid waste, and obtains 3) The foaming and micro-crystallization of the micro-crystalline foam glass can be completed with only one step of firing, and the proportion of micro-crystalline foam in which the glass phase and the micro-crystalline phase coexist can be obtained; The microcrystalline foam glass has excellent performance and meets the national A-level fireproof material standard.

The method provided by the invention is easy to realize industrialization, uses solid waste as raw material, meets the development requirements of national energy conservation and emission reduction, can realize large-area one-time firing in a tunnel kiln, can be arbitrarily cut according to requirements, and can be used in thermal insulation materials, fireproofing materials, building materials and other fields are widely used.

Detailed ways

The content of the present invention is further described and supplemented below in conjunction with specific embodiments.

The high-silicon iron tailings in the embodiment of the present invention contain 81.32% of SiO ₂ , 0.61% of Al ₂ O ₃ , 14.79% of Fe ₂ O ₃ , 0.48% of CaO, 0.32% of Na ₂ O , 0.07% of TiO ₂ and MgO by mass percentage. 0.74%, _K2O 0.14%.

The blast furnace slag in the embodiment of the present invention contains 31.01% of _SiO2 , 15.67% _{of Al2O3} , 0.54% of _Fe2O3 , 43.42% of CaO, 0.488% of Na2O, 0.566 _% of _TiO2 , _06.36 % of MgO by mass percentage, K ₂ O 0.292%.

The high-silicon iron tailings and blast furnace slag in the embodiment of the present invention are powders, and the particle size is less than 0.124 mm.

The particle size of the clay used in the examples of the present invention is less than 0.074 mm.

Titanium dioxide (TiO ₂ ), borax (Na ₂ B ₄ O ₇ ·10H ₂ O), sodium metaphosphate, Na ₂ CO ₃ and CaCO ₃ used in the examples of the present invention are commercially available products.

The particle size of the powder particles in the embodiments of the present invention is less than or equal to 0.5 mm.

The mold used in the embodiment of the present invention is an assembled refractory brick kiln furniture.

The heating furnace used in the embodiment of the present invention is a medium temperature furnace.

In the embodiment of the present invention, the weight percentage of water in the slurry is 30-40%.

The glassy phase and the crystallite phase coexist in the microcrystalline foam glass in the examples of the present invention.

Example 1

Prepare high-silicon ferrous tailings, high-alumina fly ash and clay as raw materials. In the raw materials, by mass percentage, high-silicon ferrous tailings account for 44.38%, blast furnace slag accounts for 38.94%, and clay accounts for 16.68%;

Prepare titanium dioxide, borax, sodium carbonate, calcium carbonate and sodium metaphosphate as additives; in the additives, titanium dioxide accounts for 2% of the total mass of all raw materials, borax accounts for 3% of the total mass of all raw materials, and sodium carbonate accounts for 6% of the total mass of all raw materials. %, calcium carbonate accounts for 4% of the total mass of all raw materials, and sodium metaphosphate accounts for 1% of the total mass of all raw materials;

All raw materials and additives are mixed to form a mixed material, then wet-milled with a ball mill, mixed evenly and made into a slurry; the mass ratio of water, mixed material and grinding balls during wet grinding is 0.5:1:4;

The slurry is injected into the spray granulator for spray granulation to make powder particles;

The powder particles are filled into the mold, and then placed in a heating furnace for roasting and foaming; the temperature regime in the process of roasting and foaming is as follows: the furnace temperature rises from room temperature to 900°C at a rate of 10°C/min , hold for 20min, then rise to 1140°C at a heating rate of 4°C/min, and hold for 75min;

After the calcination foaming and crystallization process is completed, it is cooled to room temperature with the furnace to obtain the microcrystalline foam glass; the bulk density of the microcrystalline foam glass is 0.48g/cm ³ , the compressive strength is 2.5MPa, and the thermal conductivity is 0.18W/(m ·K).

Example 2

The method is the same as in Example 1, except that:

(1) In the raw materials, high-silicon iron tailings account for 49.2%, blast furnace slag accounts for 32.75%, and clay accounts for 18.05%; titanium dioxide accounts for 1.5% of the total mass of the total raw materials, and borax accounts for 2% of the total mass of the total raw materials. , sodium carbonate accounts for 5% of the total mass of all raw materials, calcium carbonate accounts for 5% of the total mass of all raw materials, and sodium metaphosphate accounts for 1% of the total mass of all raw materials;

(2) Rising to 850°C at a rate of 10°C/min, holding for 20 minutes, rising to 1150°C at a rate of 4°C/min, holding for 75 minutes;

(3) The bulk density of the microcrystalline foam glass is 0.52 g/cm ³ , the compressive strength is 2.9 MPa, and the thermal conductivity is 0.21 W/(m·K).

Example 3

(1) According to the mass percentage of raw materials, high-silicon iron tailings account for 40%, blast furnace slag accounts for 44%, and clay accounts for 16%; titanium dioxide accounts for 3% of the total mass of all raw materials, and borax accounts for 4% of the total mass of all raw materials. , sodium carbonate accounts for 2% of the total mass of all raw materials, calcium carbonate accounts for 6% of the total mass of all raw materials, and sodium metaphosphate accounts for 0.5% of the total mass of all raw materials;

(2) Rising to 850°C at a rate of 8°C/min, holding for 25min, then rising to 1100°C at a heating rate of 3°C/min, holding for 100min;

(3) The bulk density of the microcrystalline foam glass is 0.45 g/cm ³ , the compressive strength is 4.5 MPa, and the thermal conductivity is 0.15 W/(m·K).

Example 4

(1) According to the mass percentage of raw materials, high-silicon iron tailings account for 46%, blast furnace slag accounts for 35%, and clay accounts for 19%; titanium dioxide accounts for 2% of the total mass of all raw materials, and borax accounts for 3% of the total mass of all raw materials. , sodium carbonate accounts for 7% of the total mass of all raw materials, calcium carbonate accounts for 1% of the total mass of all raw materials, and sodium metaphosphate accounts for 1.5% of the total mass of all raw materials;

(2) Rising to 950°C at a rate of 9°C/min, holding for 25min, then rising to 1200°C at a heating rate of 5°C/min, holding for 60min;

(3) The bulk density of the microcrystalline foam glass is 0.67 g/cm ³ , the compressive strength is 2.1 MPa, and the thermal conductivity is 0.3 W/(m·K).

Example 5

(1) In the raw materials, high-silicon iron tailings account for 50%, blast furnace slag accounts for 39%, and clay accounts for 11%; titanium dioxide accounts for 1% of the total mass of all raw materials, and borax accounts for 4% of the total mass of all raw materials. , sodium carbonate accounts for 3% of the total mass of all raw materials, calcium carbonate accounts for 3% of the total mass of all raw materials, and sodium metaphosphate accounts for 1.5% of the total mass of all raw materials;

(2) Rising to 980°C at a rate of 11°C/min, holding for 30min, then rising to 1120°C at a heating rate of 4°C/min, holding for 80min;

(3) The bulk density of the microcrystalline foam glass is 0.61 g/cm ³ , the compressive strength is 3.4 MPa, and the thermal conductivity is 0.24 W/(m·K).

Claims (2)

1. a method for preparing microcrystalline foam glass from high silicon iron tailings and blast furnace slag, is characterized in that carrying out by the following steps: (1) Prepare high-silicon ferrous tailings, blast furnace slag and clay as raw materials. In the raw materials, high-silicon ferrous tailings account for 40~50%, blast furnace slag accounts for 35~44%, and clay accounts for 11~19% by mass percentage; The high-silicon iron tailings contain 81~82% SiO ₂ , 0.6~0.7% Al ₂ O ₃ , 14~15% Fe ₂ O ₃ , 0.4~0.5% CaO, 0.3~0.4% Na ₂ O , TiO ₂ 0.05~0.1%, MgO 0.7~0.8%, K ₂ O 0.1~0.2%, and the rest are impurities; the blast furnace slag contains SiO ₂ 31~32% by mass percentage, Al ₂ O ₃ 15~16%, Fe ₂ O ₃ 0.5~0.8%, CaO 43~44%, Na ₂ O 0.4~0.5%, TiO ₂ 0.5~0.6%, MgO 0.3~0.4%, K ₂ O 0.2~0.3%, the rest are impurities; (2) Prepare titanium dioxide, borax, sodium carbonate, calcium carbonate and sodium metaphosphate as additives; titanium dioxide in the additives accounts for 1~3% of the total mass of all raw materials, borax accounts for 2~4% of the total mass of all raw materials, and sodium carbonate It accounts for 2~7% of the total mass of all raw materials, calcium carbonate accounts for 1~6% of the total mass of all raw materials, and sodium metaphosphate accounts for 0.5~1.5% of the total mass of all raw materials; (3) Mix all raw materials and additives to form a mixed material, then wet-mill with a ball mill, mix evenly and make a slurry; the weight percentage of water in the slurry is 30-40%; (4) inject the slurry into the spray granulator for spray granulation to make powder particles; (5) The powder particles are filled into the mold, and then placed in the heating furnace to carry out the process of baking foaming and crystallization; the temperature regime in the process of baking foaming and crystallization is: the furnace temperature is from room temperature to 8~11℃ The rate of heating is increased to 850~980℃/min, and the temperature is kept for at least 20min, and then it is increased to 1100~1200℃ at the heating rate of 3~5℃/min, and the temperature is maintained for 60~100min; (6) After the calcination foaming and crystallization process is completed, it is cooled to normal temperature with the furnace to obtain microcrystalline foam glass. 2. the method for preparing microcrystalline foam glass according to a kind of high silicon iron tailings and blast furnace slag according to claim 1, is characterized in that the bulk density of described microcrystalline foam glass is 0.45～0.67g/cm ³ , resistant to The compressive strength is 2.0~4.5MPa, and the thermal conductivity is 0.15~0.3W/(m·K).