CN1135946A

CN1135946A - Preparation of reductive ilmenite powder for welding rods

Info

Publication number: CN1135946A
Application number: CN 95104658
Authority: CN
Inventors: 黄时鸿; 曾光丽; 严子直; 马兴兵; 林启; 蒋淑全
Original assignee: XISHAN WELDING ROD MATERIALS FACTORY KUNMING CITY
Current assignee: XISHAN WELDING ROD MATERIALS FACTORY KUNMING CITY
Priority date: 1995-05-15
Filing date: 1995-05-15
Publication date: 1996-11-20

Abstract

A process for preparing reduced ilmenite powder used for welding electrode features that not calcined ilmenite concentrate containing TiO2 (greater than 47%) and P (less than 0.03%) and the reducing agent prepared by mixing powdered coke and limestone are alternatively loaded in refractory jar layer by layer and reduction reaction takes place then at 1200+/-100 deg.C for 20-30 hr. Its advantages are simple technology and high quality.

Description

Preparation method of reduced ilmenite powder for welding electrode

Thepresent invention belongs to the technical field of preparing metal by reducing titanium concentrate with a solid carbon reducing agent.

At present, no technique for preparing reduced ilmenite for welding electrodes exists abroad. The patent with publication number CN1036228A in China discloses a preparation method and application of reduced ilmenite powder. According to the patent specification, firstly titanium concentrate is oxidized at the temperature of 790-890 ℃, and then a reducing agent with the particle size of 0-15 mm is doped to carry out high-temperature reduction on the ferrotitanium powder, wherein in the reduction process, the first stage is kept at the high temperature of 1140 +/-25 ℃ for 4 hours, and the second stage is kept at the high temperature of 1240 +/-25 ℃ for 36 minutes. The reduction of titanium concentrate by this method has the following drawbacks: 1. the process is complex and has many steps; 2. the adoption of the solid carbon reducer by the bituminous coal is not feasible and can generate slag bonding; 3. the method is only suitable for the titanium concentrate with FeO/Fe2O3 being more than or equal to 5, and has the limitation of raw material selection; 4. because FeO in the product is less than or equal to 9 percent, the reduced product can only reach FTH920, belongs to a second-grade product and is difficult to be upgraded.

The invention provides a method for preparing reduced ilmenite powder, which is not limited by raw materials, has simple process, does not slag a reducing agent, has low product cost and can reach the quality product of more than the national standard GB5688-85 first-grade product standard, and aims to overcome the defects of the prior art and the CN1036228A patent technology.

The invention is realized by adopting the following technical scheme:

the adopted ilmenite contains TiO2 (titanium dioxide) more than or equal to 47 percent and P (phosphorus) less than or equal to 0.03 percent, and is directly reduced by filling a reducing agent formed by mixing coke powder and limestone powder and titanium concentrate into a refractory material tank in a layered and spaced mode at high temperature of 1200 +/-100 ℃ for 20-30 hours without oxidizing roasting. The content of fixed carbon in the coke powder which forms the reducing agent is more than or equal to 70 percent, the content of CaCO3 in the limestone powder is more than or equal to 90 percent, the coke powder and the limestone powder are sieved by 20 meshes, and the coke powder and the limestone powder are mechanically mixed according to the volume ratio of 8 to 1. The titanium concentrate and the reducing agent can be placed in the refractory material tank in an interlayer mode, namely a vertical installation mode (as shown in figure 1) or a horizontal installation mode (as shown in figure 2), a layer of reducing agent is paved on the inner wall and the port of the refractory material tank, the thickness of the iron concentrate is less than or equal to 30mm when the vertical installation mode is adopted, the thickness of the alternate reducing agent is more than or equal to 10mm, the thickness of the titanium concentrate is less than or equal to 20mm when the horizontal installation mode is adopted, and the thickness of the alternate reducing agent is more than or equal to 7 mm.

The invention is further explained by the following figures and examples in conjunction with the description:

FIG. 1 is a schematic view of the method of the present invention in a vertical position;

FIG. 2 is a schematic view of a flush mounting mode of the process of thepresent invention;

FIG. 3 is a schematic time-temperature diagram according to an embodiment of the present invention;

FIG. 4 is a schematic view of a kiln body;

FIG. 5 is a sectional view of the kiln mold.

The reference numbers in the drawings are: 1-iron ore concentrate, 2-reducing agent, 3-refractory material tank, 4-temperature rising section, 5-heat preservation section, 6-temperature reduction section and 7-kiln car.

The invention has no requirement on the ratio of FeO/Fe2O3, and can obtain qualified high-quality products only by once reduction without oxidizing roasting as long as TiO2 is more than or equal to 47 percent and P is less than or equal to 0.03 percent in the raw materials. The specific embodiment is to select the flush mounting mode as shown in figure 2. Composition of all titanium concentrates: a layer of 18mm thick TiO248.2%, FeO 34%, Fe2O313.4% and P0.007% is laid on the bottom layer of the refractory material tank 3, a layer of reducing agent 2 with 15mm thick is filled on the whole inner side of the refractory material tank, and the reducing agent is formed by sieving two materials of coke powder with the fixed carbon content of 72% and limestone powder with the CaCO3 content of 90% through a 20-mesh sieve. Mechanically mixing the coke powder and limestone powder in the volume ratio of 8 to 1. The volume ratio of the titanium concentrate 1 to the reducing agent 2 in the refractory tree charging bucket 3 is about 1: 1, and the titanium concentrate and the reducing agent can be separated by common paper to improve the recovery rate of the titanium concentrate. The ports of the refractory material tank are also covered with a layer of reducing agent to isolate the contents of the tank from air as much as possible. And then heating the tank body for 20-30 hours at a high temperature of over 1100 ℃, wherein the heating temperature is generally not more than 1300 ℃. Otherwise, the tank body is easy to deform and break, the furnace kiln for heating is a tunnel kiln, the length of the kiln is more than 60m, for example, 66m, the height multiplied by the width of the tunnel is 12m multiplied by 1.2m, the kiln is divided into three sections, the heating section is 4 m long and 18m long, the heating section is a preheating section, the heat preservation section is 5m long and 36m long, the heating section is a high temperature section, the cooling section is 6m long and 12m long, and the cooling section is a cooling. The length of the kiln car is 2 m. The kiln car 7 is used for carrying the refractory tree material tank 3, the kiln car is pushed every 1.5 hours, the titanium concentrate and the reducing agent are heated and reduced at a high temperature section once, and the chemical reaction formula is as follows:

6.04TiO2+4.75FeO +0.845Fe2O3+6.645CO → 1100-1300 ℃ for 20-30 hours → 6.04TiO2+0.64FeO +5.8Fe +6.645CO2

The cooling section 6 is a cooling section, when the temperature is reduced to below about 990 ℃, the furnace can be discharged, then the tank body is cooled rapidly by forced air cooling, and the reduced metallic iron is prevented from being reoxidized due to the fact that the CO concentration in the tank is reduced to below 60 percent caused by imperfect sealing. When the temperature of the materials in the tank is cooled to below 50 ℃, the reduced ilmenite which is agglomerated in the tank can be taken out and then crushed by a crusher. Sieving with 40 mesh sieve, and removing nonmagnetic substances by magnetic separation to obtain reduced ilmenite powder product.

Compared with the prior art, the invention has the obvious advantages of no limitation of raw materials, simple process, low product cost and high quality.

The performance of the ilmenite powder prepared by the method is shown in the following table after detection:

composition (A) Sample	TiO2	C	FeO	S	P	TFe	MFe
composition (A) Sample	TiO2	C	FeO	S	P	TFe	MFe	Products of the invention	53.2	0.16	4.72	0.002	0.0077	39.17	35.48
TH7.20	≥54	≤0.20	≤7.0	≤0.03	≤0.03			Products of the invention	53.2	0.16	4.72	0.002	0.0077	39.17	35.48
TH7.20	≥54	≤0.20	≤7.0	≤0.03	≤0.03			TH9.20	≥52	≤0.20	≤9.0	≤0.035	≤0.04

Claims

1. A process for preparing reduced ilmenite powder for welding electrode. The method is characterized in that ilmenite powder and a solid carbon reducing agent are interlaminar loaded into a refractory material tank and reduced at high temperature to obtain the ilmenite carbon reducing agent, and the method is characterized in that: TiO2 (titanium dioxide) in the adopted titanium concentrate 1 is more than or equal to 47 percent, P (phosphorus) is less than or equal to 0.03 percent, and the titanium concentrate is directly layered and spaced with a reducing agent 2 formed by mixing coke powder and limestone powder without oxidizing roasting and is filled into a refractory material tank body 3, and the titanium concentrate is reduced at the high temperature of 1200 ℃ plus 100 ℃ for 20-30 hours.

2. The method of claim 1, further comprising: the content of fixed carbon in the coke powder which forms the reducing agent is more than or equal to 70 percent, the content of CaCO3 in the limestone powder is 90 percent, the coke powder and the limestone powder are sieved by 20 meshes, and the volume ratio of the coke powder to the limestone powder is 8: 1.

3. The method of claim 1, further comprising: the titanium concentrate 1 and the reducing agent 2 are arranged at intervals in the refractory material tank 3 in a vertical or horizontal mode, and a layer of reducing agent is paved on the inner wall and the port of the refractory material tank.

4. The method of claim 3, wherein: when the vertical installation mode is adopted, the thickness of the titanium concentrate is less than or equal to 30mm, and the thickness of alternate reducing agents is more than or equal to 10 mm; when the flat loading mode is adopted, the thickness of the titanium concentrate is less than or equal to 20mm, and the thickness of alternate reducing agents is more than or equal to 7 mm.