CN1118379A

CN1118379A - Melting process and special furnace for high grade silica-calcium alloy

Info

Publication number: CN1118379A
Application number: CN 94109208
Authority: CN
Inventors: 王文祥; 党文
Original assignee: MUNICIPAL COLLECTIVE ECONOMIC INDUSTRY AND TRADE Co GANSU PROV
Current assignee: MUNICIPAL COLLECTIVE ECONOMIC INDUSTRY AND TRADE Co GANSU PROV
Priority date: 1994-09-05
Filing date: 1994-09-05
Publication date: 1996-03-13

Abstract

The process for producing high-grade Si-Ca alloy using special smelting furnace includes such technical steps as calculating the consumptions of calcium lime, silica and coke based on reaction equation, adding fluorspar whose consumption is 10% of the total quantity of the said three materials, breaking, and smelting in special graphite crucible having central vertical inducing graphite rod and graphite liner of 2-4 cm in thickness on its internal wall. Its advantages include avoiding furnace expansion, easily controlling furnace temp., and high Ca content in the alloy (more than 31%).

Description

Smelting method of high-grade silicon-calcium alloy and special smelting furnace

The invention relates to a method for smelting high-grade silicon-calcium alloy, in particular to a method for smelting silicon-calcium alloy in an electric furnace.

At present, the method for smelting the silicon-calcium alloy at home and abroad adopts a three-phase electric arc furnace, the smelting furnace is not sealed, and an open system is formed, so that the smelted materials in the furnace are directly contacted with air. The three-phase arc furnace has the advantages that the furnace temperature in the crucible area is higher, the furnace temperature in the furnace wall area is lower, the furnace temperature in the furnace is very uneven, the furnace expansion phenomenon can be caused, the power consumption is increased, and the service life of the electric furnace is also reduced. The raw materials of the silicon-calcium alloy smelted by the three-phase arc furnace are blocky and are put into the furnace in a layered mode, and the temperature in the furnace is uneven, so that the reducing agent is not easy to generate reduction reaction with other materials. There is also a case where calcium in the high temperature region is volatilized and calcium in the low temperature region is not reacted with other substances. Therefore, the process and the equipment can not ensure the increase of the calcium content in the silicon-calcium alloy, and the silicon-calcium alloy with the calcium content of more than 31 percent can not be produced, and the higher the calcium content of the silicon-calcium alloy is, the higher the use value is.

The invention aims to provide a method and a special smelting furnace for producing Si-Ca alloy with calcium content of more than 31%.

A smelting method of high-grade Si-Ca alloy includes such steps as preparing raw materials, proportioning, smelting and discharging, and choosing calcium lime, coke or charcoal, silica or silicon slag as raw materials

The required quantity of quicklime, coke or charcoal, silica or silicon slag is calculated by the equation, which is characterized in that the quicklime, coke or charcoal, silica or silicon slag are respectively crushed into powder with the granularity of 80-200 meshes by a common crusher, and then fluorite (C) is added_aF₂) Also pulverizingThe method is characterized in that 80-200 meshes of powder is prepared by uniformly mixing the powder, then adding the powder into a special smelting furnace, wherein the feeding amount of fluorite is 10% of the total feeding amount of lime, coke or wood carbon and silica or silicon slag, covering the added material with 1-2 cm of coke powder or wood carbon powder, closing a top cover (1) of the special smelting furnace, raising the temperature of the furnace to 980-1400 ℃, and smelting for 1.5 hours. The quicklime, coke or charcoal, silica or silicon slag and fluorite are crushed or fed, so that the reducing agent and other materials can fully react to smoothly deoxidize.

A special smelting furnace for smelting high-grade silicon-calcium alloy comprises a furnace body (1) and a graphite crucible (2), and is characterized in that a vertical graphite induction rod (4) is arranged in the middle of a graphite crucible, a graphite lining (3) with the thickness of 2-4 cm is coated in the graphite crucible, and a furnace top cover (5) is arranged at the top of the furnace body. The graphite lining (3) is coated on the inner wall of the graphite crucible (2), and the graphite induction rod (4) is arranged in the crucible, so that the temperature in the furnace is uniform and easy to control, and the influence on the grade of the silicon-calcium alloy caused by the first volatilization of calcium in a region with high temperature in the furnace is avoided. The furnace top cover (5) is covered to ensure that the reaction in the furnace is completed more completely without causing the phenomenon of furnace expansion.

The invention adopts a material crushing method and a special smelting furnace, so that the raw materialscan be smelted at a uniform temperature after being put into the furnace, the chemical reaction in the furnace is completed completely, the volatilization of calcium is reduced, the furnace expansion phenomenon is not generated, the power consumption is reduced, the grade of the product is improved, and the high-grade silicon-calcium alloy with the calcium content of more than 31 percent can be produced.

FIG. 1 is a structural sectional view of a special melting furnace of the present invention

FIG. 2 is a top view of the special melting furnace of the present invention

The invention is further illustrated by the following two embodiments in conjunction with fig. 1 and fig. 2:

example 1:

it is required to produce a silicon-calcium alloy containing 48% of calcium. The total amount of flutolite is 1000 kg, and 100 kg of flutolite. Firstly, the original intermediate frequency electric furnace is reformed into a special smelting furnace. The inner wall of the heat insulation protective layer of the original medium frequency electric furnace is coated with a graphite lining (3) of 2-4 cm, a vertical graphite induction rod (4) is arranged in a graphite crucible, and the top of a smelting furnace is provided with an openable top cover (5).

615.38 kg of slag after the production of silicon-calcium alloy by a submerged arc furnace, 153.85 kg of quicklime, 230.77 kg of silica, 190.65 kg of reducing agent coke powder and 100 kg of flux fluorite are respectively crushed into 80-200 mesh powder, the powder is uniformly mixed and stirred, 150 kg of the stirred mixed powder material is taken out and added into a special modified smelting furnace, 2 cm of coke powder is covered on the surface of the material, a top cover is covered, the furnace temperature is controlled between 980 ℃ and 1200 ℃, the smelting is carried out for 1.5 hours, and the material is discharged. The analyzed product had a calcium content of 48.17% and a silicon content of 42.21%.

Example 2:

the silicon-calcium alloy with the calcium content of about 55 percent needs to be smelted, the dosage is 1000 kg, and the silicon-calcium alloy does not contain reducing agent and flux.

Because the calcium content requirement is different, the proportioning quantity of the raw materials calculated according to the equation is also different, wherein the amount of the slag is 571.43 kg, the amount of the quicklime is 285.71 kg, the amount of the silica is 142.86 kg, the amount of the reducing agent coke powder is 193.94 kg, and the amount of the fluxandrite is 100 kg. The whole process is the same as in example 1. The quantity of raw materials fed into the smelting furnace each time can be determined according to the size of the smelting furnace, and the smelting temperature can be controlled to be 1000-1400 ℃. After the product is discharged from the furnace, analysis is carried out: the calcium content is 57.13%, and the silicon content is 37.72%.

Claims

1. A smelting method of high-grade Si-Ca alloy includes such steps as preparing raw materials, proportioning, smelting and discharging, and choosing calcium lime, coke or charcoal, silica or silicon slag as raw materials

The formula is used to calculate the ratio of calcium lime, coke or charcoal, silica or silicon slag, and is characterized by that the calcium lime, coke or charcoal, silica or silicon slag are respectively pulverized into the powder whose grain size is 80-200 meshes by means of ordinary pulverizer, then the fluorite (C) is added_aF₂) And the materials are also crushed into 80-200 meshes of powder, the powder is evenly mixed and then is put into a special smelting furnace, the feeding amount of the fluorite is 10 percent of the total feeding amount of the quicklime, the coke or the wood carbon and the silica or the silicon slag, the fed materials are covered with 1-2 cm of coke powder or wood carbon powder, a top cover (1) of the special smelting furnace is closed, the temperature of the furnace is raised to 980-1400 ℃, and the smelting is carried out for 1.5 hours.

2. A special smelting furnace for smelting high-grade silicon-calcium alloy comprises a furnace body (1) and a graphite crucible (2), and is characterized in that a vertical graphite induction rod (4) is arranged in the middle of a graphite crucible, a graphite lining (3) with the thickness of 2-4 cm is coated in the graphite crucible and the graphite crucible, and a furnace top cover (5) is arranged at the top of the furnace body.