Titanium Slag Electric Furnace Smelting Principle

 

Titanium slag production employs an electric furnace smelting process (classified by shape into circular and rectangular furnaces). Titanium slag electric furnace can be categorized into three types based on their enclosure method: closed submerged arc furnace, semi-closed electric furnace smelting, and open electric furnace smelting.

The Principle of Titanium Slag Electric Furnace Smelting

1. The Principle of Titanium Slag Smelting

The principle of titanium slag production using the electric furnace method involves mixing ilmenite with a solid reducing agent (anthracite or coke, etc.) in a specific ratio and adding it to a submerged arc furnace for reduction smelting. 

Iron oxides in the minerals are selectively reduced to metallic iron, while titanium oxides are enriched in the slag. After slag-iron separation, titanium slag and the byproduct metallic iron are obtained.

2. Raw Materials for Titanium Slag Smelting

1) Ore: 

The titanium ores used for producing titanium slag include titanium concentrate, rutile titanium ore, and ilmenite. 

Titanium concentrate and rutile titanium concentrate have high TiO2 content, while ilmenite has a lower TiO2 content.

2) Reducing Agents: 

The main types of reducing agents include coal gas, charcoal, anthracite, and coke. Charcoal has excellent reactivity and resistivity, but is expensive, scarce, has high volatile matter content, and high ash content, thus it is not widely used. 

Coal gas and anthracite have slightly lower reducing properties and resistivity than charcoal, but have large reserves and are used extensively in titanium slag smelting.

However, coal gas has high volatile matter content, which is difficult to control, requiring large-scale processing equipment. Therefore, coal gas is not widely used.

Coke has low reducing properties, high carbon content, low volatile matter content, low conductivity, and large reserves, but is not used extensively in smelting. 

Therefore, anthracite is often used as a reducing agent in titanium slag smelting. The physicochemical properties of coke used are fixed as follows: C ≥ 80%, particle size 3-12mm. 

The amount of reducing agent is calculated based on the percentage of ferrous oxide and ferric oxide in the ore. The amount of reducing agent is then calculated using the redox equation for iron.

3. Batching & Feeding Principle

All ore and reducing agent are placed in a silo with two feeding ports at the bottom.

One is a rotary feeder that feeds the material, with the feed rate controlled by speed; the other is a vibrating feeder. The material is directly pressed onto the weighing belt.

As the weighing belt moves, the idler rollers receive the weight signal and transmit it to a mechanical device equipped with a weighing sensor below the rollers. The sensor transmits the received signal to the signal processing center for metering.

The titanium slag electric arc furnace uses both automatic and manual batching methods. Automatic batching involves inputting preset values ​​for parameters such as the quantity of titanium concentrate, the ratio of coke, and the batching time into a program, which then operates automatically. 

Manual batching requires manually starting each piece of equipment by inputting parameters such as the quantity of titanium concentrate, the ratio of coke, and the batching time according to smelting needs. The material is then transported by belt to a storage silo at the top of the furnace.

Submerged Arc Furnace Technology

Existing titanium slag electric arc furnaces (EAF) smelting processes are categorized by melting pool characteristics into intermittent smelting, continuous smelting, and continuous charging via the electrode cavity. Charging methods include open furnaces, closed furnaces, and semi-closed furnaces.

Different smelting processes are selected based on different requirements. Pressure control within the EAF is critical; explosion-proof vents on the furnace cover maintain a constant pressure. Thermocouples are installed at various locations within the furnace layer to measure the temperature of the refractory material and assess its erosion degree.

Once the EAF is ready for smelting, the start-up sequence is as follows: 

Furnace drying, lining preheating, slag application to the furnace walls, slag tapping, and iron tapping.

Under normal production conditions, the smelting operation sequence of an electric furnace is as follows:

• (1) Production preparation
• (2) Electric furnace start-up
• (3) Process operation
• (4) Slag tapping
• (5) Iron tapping

The main adjustments during the smelting process are:

• (1) Electrode raising and lowering, electrode setting, current adjustment, and capacitor compensation
• (2) Furnace top charging control and charging amount
• (3) Adjusting the furnace negative pressure and furnace gas temperature, etc.
• (4) Electrode control. At a certain stage of smelting, the height of the molten iron and slag layer needs to be measured.

When the iron and slag tapping adjustment is reached, the taphole and slag tapping are performed. The tapped molten iron flows to the casting machine through the molten iron channel. After tapping, the taphole is plugged. Then, slag is tapped, and the tapped slag enters the slag basin. The slag in the slag basin is transported to the slag cooling area for cooling. After tapping, the slag tapping port is plugged.

In the smelting production of submerged arc furnaces, key economic indicators need to be calculated, including titanium concentrate consumption, reducing agent consumption, electricity consumption, water consumption, refractory material consumption, electrode consumption, equipment operating rate, and product recovery rate.

The above is part of the content regarding the principle of titanium slag electric arc furnace smelting. If you have any further questions or needs, please feel free to contact us for service and feedback!

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