melting furnace

What is a melting furnace?

A melting furnace is a furnace in which the heated material is heated and melted by heat supplied from some high-temperature heating source. Tanabe offers electric resistance type, plasma type, and burner type melting furnaces, depending on the heating source. The plasma and burner types are limited in their applications and throughput, while the electric resistance type has a proven track record in a wide range of applications and throughputs.

Melting Furnace Features

The features of melting furnaces vary depending on the heating source. The features of electric resistance melting furnaces are described here.

• This method generates Joule heat and melts the material or molten slag by directly passing electricity through electrodes embedded in the material or molten slag, thereby achieving high thermal efficiency.
• Since the furnace is operated with the electrodes buried in the raw materials and molten slag, open arcs do not occur, resulting in quieter operation compared to (open) arc furnaces.
• Material charged into the furnace forms a covering layer on the top surface of the molten slag, reducing wear and tear on the furnace lid refractory due to radiant heat from the molten slag flame, and also reducing energy carried out by exhaust gas.
• Slag and metal are separated vertically in the furnace due to the difference in specific gravity, which facilitates recovery.
• No energy-derived exhaust gas volume and compact exhaust gas treatment facilities are possible.
• We can build highly reliable systems based on the technology and experience we have cultivated over many years. We can also provide equipment that can efficiently supply electricity to the melting furnace.

Principle, structure and mechanism of melting furnace

Melting furnace principle and method

Melting furnaces are classified into [electric resistance type], [plasma type], and [burner type] based on the difference in heating source.

electric resistance

As an electric resistance type melting furnace, Tanabe has been providing furnaces classified as Submerged Arc Furnace (SAF) or Direct Resistanace Furnace (DRAF) for many years and for various applications. They are called SAFs because they operate with the electrodes submerged (submerged) in the raw material or molten slag. The furnace is a melting furnace that uses the heated material as the heating source, since electricity is applied directly to the material or molten slag inserted in the furnace and the material or molten slag is heated by Joule heat.

Plasma type

As a plasma type melting furnace, Tanabe offers furnaces classified as DC arc plasma furnaces for the melting of municipal solid waste incineration ash. A plasma torch inserted inside the furnace emits high-temperature plasma jets (20,000 to 30,000°C at the center) toward the material to heat and melt it. Since the furnace is operated at a furnace pressure close to atmospheric pressure, it is a melting furnace that uses atmospheric discharge plasma (thermal plasma) as its heating source among plasma (a state in which ions and electrons are aggregated).

Burner type

As a burner type melting furnace, Tanabe offers a burner type surface reflection melting furnace for municipal solid waste incineration ash melting applications. This melting furnace uses a burner (either liquid or gaseous fuel) as the heating source. The special burner, whose flame spreads in a trumpet shape, is used, and an appropriate number of burners are arranged according to the amount of material to be processed to increase the surface melting efficiency of the material.

Structure and Mechanism of Melting Furnace

The structure and mechanism of melting furnaces differ depending on the heating source. After being transformed into high-current, low-voltage electricity in a transformer for the furnace, electricity is supplied to the melting furnace through the power feeder and electrode facility. The electrode facility has a function to raise and lower the electrodes, enabling control of the electric power (current) applied to the melting furnace. Raw materials are charged into the furnace body, which is lined with refractory material, and the materials are melted in the furnace body. The top of the furnace body is covered with a refractory-lined furnace lid. Various types of processing can be performed inside the melting furnace.

Reduction reaction treatment

The material containing oxide and reductant is melted and the temperature is raised above the reduction reaction temperature to enable a reduction reaction (application examples: melting furnace for calcium carbide production, melting furnace for ferroalloy production, melting furnace for valuable metal reduction and recycling).

volume reduction process

The volume can be reduced by melting the raw material (application example: melting furnace for municipal solid waste incineration ash).

detoxification

It is possible to immobilize some of the heavy metals in the raw material in the slag and detoxify the slag to reduce the amount of toxic substances eluted below the standard value (application example: melting furnace for melting incinerated ash from municipal waste).

melting process

The material can be discharged in a molten state to the subsequent equipment (application example: melting furnaces in general, especially melting furnaces for rock wool production).

specific gravity treatment

It is possible to melt the raw material, separate the slag and metal by specific gravity in the furnace, and discharge the slag and metal separately. furnace).

Finished metal and slag are discharged through tapped holes drilled in the side walls of the furnace by the tap opening/closing device, and are cooled and solidified in each of them. The exhaust gas generated by the melting furnace is treated in the exhaust gas treatment facility, detoxified, and discharged into the atmosphere.

Melting Furnace Product Lineup

Melting furnace for calcium carbide production

Calcium carbide (CaC2) is produced by heating a mixture of quicklime and coke to about 2000°C in a melting furnace, and is used in the industrial manufacture of acetylene, etc. It is also used as a deoxidizing and desulfurizing agent in steelmaking and smelting. View product details

Melting furnace for ferroalloy production

Ferroalloy is a general term for various alloys of iron and elements to be deoxidized or added to special steel materials (including nonferrous metals) in the steelmaking process. They are classified into two major types: enclosed type and semi-covered type.View product details

Melting furnace for valuable metal reduction and recycling (valuable metal recovery)

This is a valuable metal reduction and recycling melting furnace for carbon reduction of metal oxides and neutralized sludge contained in copper and precious metals from incineration residues of waste boards and by-products of stainless steel manufacturing processes. Metal oxides are transformed into metal by carbon reduction, and molten metal can be easily separated into metal and slag by specific gravity separation. View product details

Melting furnace for municipal solid waste incineration ash melting

This melting furnace is designed for volume reduction and detoxification of municipal solid waste incineration ash. We offer electric resistance type, plasma type, and burner type melting furnaces, depending on the heating source. The burner type is suitable for small- and medium-scale incineration facilities that do not have a waste power generation system. View product details

Melting furnace for rock wool production

This furnace is used to produce insulation material (rock wool) for various applications. There are two main types of furnaces: hot charge furnaces, which use molten slag from blast furnaces as raw material, and cold charge furnaces, which use rock as raw material. In the case of the hot charge method, a low energy intensity can be achieved. Using Tanabe's proprietary slag metering system, slag can be supplied stably to the subsequent cotton-making line, resulting in excellent product quality. View product details

Copper smelting slag furnace

The slag generated during copper smelting contains a small amount of copper metal grains, which are allowed to settle to the bottom of the melting furnace by specific gravity separation and are separated from the slag to recover copper metal. Since the slag is fed into the melting furnace in a molten state, the electricity supplied to the melting furnace is consumed mainly to keep the slag in a molten state.View product details

Melting furnace ancillary equipment lineup

Tanabe can provide engineering proposals not only for the melting furnace itself, but also for the ancillary equipment, and we can design the optimum system to meet your needs. We can also design and manufacture ancillary equipment only, so if you have any ancillary equipment you would like, please contact us.

power supply (facility)

Equipment for supplying electric power to electrodes of melting furnaces. We supply optimal equipment with reduced power loss based on our extensive experience and know-how. The design of power supply and electrode facilities requires a thorough understanding of the production volume and the electrical characteristics (temperature and intrinsic resistance) of the melt. Tanabe provides optimum equipment by designing based on data accumulated through our long and extensive track record. View product details

Electrode facilities

This equipment is used to raise and lower the electrodes of the melting furnace and to control the power. The design of power feed and electrode facilities requires a thorough understanding of the production volume and the electrical characteristics (temperature and inherent resistance) of the melt. Tanabe offers the best equipment by designing based on data accumulated over many years of extensive experience.View product details

Electrode splicer

This is a device for automatically splicing synthetic graphite electrodes (for 10- and 12-inch electrodes). By introducing the electrode splicing device, it is possible to automate the process of manually splicing electrodes.View product details

Furnace body tilting device

A device used to tilt the furnace body of a melting furnace to discharge molten materials from the furnace. This is an incidental equipment used in cases where the tap opening is not suitable for discharging molten metal.View product details

Furnace Weight Weighing System

The furnace weight of the melting furnace is weighed and used to control the amount of raw material charged and the amount of slag and metal discharged. In principle, it cannot be installed simultaneously with the furnace body tilting device.View product details

Slag fixed-quantity pouring system

This device controls the amount of slag output. This device is mounted on a melting furnace when it is desired to control the amount of slag received at a later stage facility of slag discharge.View product details

Tap opening/closing device (Drilling machine / Mud gun)

This is an automatic tap opening/closing device used when metal and slag are discharged. A drilling machine drills a hole in the side wall of the furnace body to discharge hot metal. When it is necessary to stop the pouring, a mud gun is used to fill the tap hole in the side wall of the furnace body with mud.View product details

Equipment for cooling and solidifying molten materials

This equipment cools and solidifies metal and slag discharged from the melting furnace. We offer various types of systems, such as the straight endless type, cart-moving type, and circular type. In the endless type, the cooled material is peeled off and dropped by mold inversion at the head. In the circular type, the mold is peeled off through the mold reverser.View product details

Slag conveyor

This is a casting system for slag discharged from the melting furnace.View product details

Duct cleaning equipment

This device is used to remove exhaust gas dust adhering to the melting furnace flue (duct). The tip of the device automatically moves back and forth inside the duct while rotating, and removes dust that has adhered to and accumulated on the duct.View product details

Furnace cover equipment

We provide furnace covers suitable for operation of various types of melting furnaces, from large furnaces to small furnaces, according to customer requirements. The inner surface of the furnace lid is lined with refractory material, but we can also provide the furnace lid can body only.View product details

Flow of Introduction

• (In the case of raw materials that Tanabe has never handled before, we will conduct verification tests and proceed with the specification review.)
• Propose equipment specifications and equipment costs to the client.
• Once we receive an order from the customer, we start designing and manufacturing.
• If there are any changes to your order, repeat steps 1 through 3 above according to the changes.
• After the production is completed, the equipment is delivered to the site, installed and commissioned, and then the equipment is installed.

verification test

In the verification test, it is possible to confirm the melting feasibility of the melting object, the melting status (melting point, fluidity, etc.), the reduction status if there is a reduction reaction, and the slag specific resistance value required for the design of the actual melter. Tanabe has a demonstration testing machine for the introduction of actual melting furnaces, which is currently under renewal.

Specifications before renewal

Transformer capacity: 100kVA three-phase AC power supply
Inner dimensions of furnace: φ660 x H400mm
Electrode diameter: 4 inches (artificial graphite)
Melting temperature: 1200°C to 1500°C (please consult with us according to the materials to be processed)

Flow of Testing Efforts

• meeting: We will discuss the test purpose and desired conditions at the meeting.
• Test plan drafting: Based on the results of the meeting, we propose a test plan that the customer desires.
• test run: We will conduct a test in the presence of the customer. Batch method is supported (8 hours/day operation).
• Summary of result evaluation data: Organize data such as temperature conditions and processing time, and evaluate the results against the plan.
• Reflected in the equipment specifications of the actual machine: The test results are reflected in the equipment specifications, and the equipment specifications are proposed.

Verification test list

After-sales service

We will enhance the outer service after delivery of the melting furnace and contribute to the creation of the optimal operating environment for our customers.

Main after-sales service

regular maintenance
We propose the best maintenance according to the customer's shutdown period.
・Cleaning and replacing the seal part
・Replacement of spare parts and consumables
spare parts sales
We have various consumables and spare parts necessary for stable and continuous operation. We also offer equipment diagnosis during regular maintenance.
Support for remodeling work
We are carrying out remodeling work to realize further functions, such as remodeling the in-furnace mechanism to strengthen production capacity and change products.

FAQ

How are the ingredients dissolved?

The raw material heated by the heating source gradually rises in temperature, and when the temperature rises to the melting point of the raw material, it gradually melts from the surface of the raw material.

What kind of raw materials can be melted?

In the electric resistance melting furnace, the main heating medium is molten slag, so it cannot be melted unless there is a component that forms the basis of molten slag in the raw material components, or if molten slag is not always kept in the furnace. . Also, depending on the composition of the molten slag, it may not be suitable for the melting furnace, so please contact Tanabe with information on the raw material you want to melt and inquire. target).

What is the maximum size of the melting furnace? Also, what is the maximum temperature?

We have a track record of melting furnaces (melting furnaces for manufacturing ferroalloys) with an inner diameter of 12.6m and a depth of 5.6m as the maximum size of the melting furnace. The maximum temperature of the melting furnace is about 2000℃ (melting furnace for manufacturing calcium carbide).

How does the melting furnace keep its shape when the raw material is melted at high temperature?

A refractory is installed inside the furnace body of the melting furnace, and this refractory is selected from materials that can withstand high temperatures, so it can be used as a melting furnace. In addition, the refractory can be used for as long as possible by cooling the furnace shell (called steel shell) with water.

How much does it cost to install a melting furnace?

It varies depending on the purpose and size of the melting furnace and the presence or absence of ancillary equipment, and raw material costs have continued to rise recently, so please inquire individually.

I would like to know the delivery record, can you tell me?

We have a track record of delivery in industries such as iron and steel (alloy ferrous), non-ferrous smelting, metal recycling, and waste disposal. Please contact us for the details of delivery record.

What are melting furnaces used for?

Reduction reaction treatment, volume reduction treatment, detoxification treatment, melting treatment, and gravity separation treatment are possible. For specific applications, Structure and Mechanism of the Melting Furnace AbovePlease refer to.

How do you get the melted stuff out?

The material melted in the melting furnace is taken out by drilling the tap opening on the side wall of the furnace body with a drilling machine. By changing the height position of the tap mouth, it is possible to take out only the metal or only the slag.

The raw materials contain moisture. Is it okay to put them into the melting furnace as they are?

If the raw material contains water, the evaporated water will accelerate the wear of the electrodes and refractories.

Do you handle (open) arc furnaces as products?

(Open) arc furnaces (Electrode Arc Furnace; EAF) are not handled by Tanabe.

What are the advantages of your melting furnace?

Based on the technology and achievements we have cultivated over many years, we are able to build a highly reliable system and provide equipment that can efficiently supply electricity to the melting furnace.