Silicon Melting

Resistive radiant heating elements are currently used for many processes in silicon production and limit the heating/melting rate of silicon. Induction furnaces, however, with their ability to deliver heat directly or indirectly into a mass of silicon, make them the preferred choice for the next generation of thermal equipment for solar-grade silicon production.

Coreless Induction Furnaces

Inductotherm’s coreless induction furnaces offer superior performance and outstanding durability, and are more efficient, more productive, quieter and easier to maintain than competitive furnaces. They are ideal for melting all metals, including silicon.

diagram of coreless induction furnace
  1. Heavy steel shell provides maximum furnace rigidity and strength for long lining life, low furnace noise and minimum EMF emissions.
  2. Induction coil is split into two or three sections to create a “running” electromagnetic wave that causes vigorous stirring of the molten bath.
  3. Electromagnetic shunts cover more that 50% of the coil’s circumference, redirecting the electromagnetic field into the melt.
  4. Graphite susceptor lining carries the current and heats the metal before the molten silicon becomes conductive.
  5. Optional vacuum cap creates controlled environment for gas purging to remove boron and phosphorous from molten silicon.
  6. Casting spout pours silicon into molds or kettles to harden before further refining.

Unidirectional Stirring

diagram of Unidirectional Stirring in an Induction Melting Furnace

Ingot producers depend on Inductotherm’s systems for melt flexibility and product uniformity. For ingot makers, the correct amount of induction stirring is a key factor in producing ingots that are metallurgically homogeneous from the start to the finish of each batch. Our induction melting systems are designed to produce the best level of stirring for each customer’s application.

Vacuum and Controlled Atmosphere Systems

Some processes require that silicon be refined to a high level of purity. This can be achieved in large quantities using Inductotherm’s vacuum and controlled atmosphere systems, custom designed to meet the requirements of each of our customer’s process needs.

Induction Melt Systems Designed for Controlled Atmospheres

Our vacuum cap furnaces are ideal for the removal of boron and phosphorus from bulk silicon by gas purging or vacuum evaporation.

Inductotherm Melt Benefits:

  • Superior Performance and Durability of Our Coreless Melting Furnaces
  • Smaller Chamber for Rapid Evacuation of Gasses
  • Designed for Vacuum or Pressure Controlled Atmosphere

Induction Melt Systems Designed for Vacuum Atmospheres

Our Vacuum Induction Melting (VIM) systems are the leading vacuum induction melt systems used in production today. VIM systems use and induction furnace, located in a vacuum/inert atmosphere chamber, to charge, melt, refine and cast silicon material; this allows for the chemistry to be continually adjusted until the precise purity is achieved. Impurities are removed by chemical reaction, disassociation, flotation and volatilization.

Inductotherm Melt Benefits:

  • Ability to Melt and Cast in Vacuum or Controlled Atmosphere
  • Multiple Charging Systems for Rapid Melting of Silicon Charge
  • Extensive Data Acquisition through the Latest PLC and PC SCADA Monitoring Controls
  • Designed for Vacuum or Pressure Controlled Atmosphere
Electromagnetic Cold Crucible (EMCC)

Inductotherm manufactures electromagnetic cold crucible furnaces for the refining of metallurgical grade silicon and the casting of multicrystalline silicon ingots. Our innovative process utilizes a segmented water-cooled copper crucible for refractory-free induction melting. We are always improving, developing, and refining EMCC Technology to increase its efficiency.

Features of Our Electromagnetic Cold Crucible Furnaces:

  • Robust Segmented Copper Crucible Machined from a Single Forging
  • Frequency Machined Induction EMCC Power Supplies
  • Stirring Inherent with Refining in the EMCC Promotes Homogenous Mixing in the Melt
  • Computer Controlled Withdrawal Rate Provides Five Times the Growth Rate than that of a Traditional Multicrystalline Directional Solidification Casting Furnace

Power Supplies and System Components

The use of our induction technology in applications such as the Fluidized Bed Reactor and Crystal Pulling has revolutionized the Photovoltaic Industry, allowing for energy efficient and controllable power to create high quality multicrystal and monocrystal silicon ingots.

Multi-SwitchTM Power Systems for Fluidized Bed Reactors

In the fluidized bed process, pure silicon pellets are grown from tiny pure silicon seeds into polysilicon granules in a high-temperature reaction vessel.

To dramatically increase the yield of these high-temperature reaction vessels, also called fluidized bed reactors, Inductotherm developed a special multi-zone coil and patented Multi-SwitchTM power supply. This system allows time-sharing of the power from a single inverter and applies it to different coil zones, thereby supplying variable and adjustable energy flow to various sections of the susceptor.

Complete Systems for Silicon Melting

More than Furnaces

  • Water Cooling Systems
  • Induction Power Supplies
  • Computer Control Systems
  • Ground Leak Detection
  • Robotic Slagging

Contact Us today and learn more.

Our Coreless Furnaces combine high productivity with maximum alloy flexibility.

Our Heavy Steel Shell Furnaces are more efficient, more productive, quieter and easier to maintain than competitive furnaces.

The creation and casting of super alloys and other advanced and reactive metals requires sophisticated induction systems for vacuum and controlled atmosphere melting and remelting systems.

Our world famous family of VIP® induction power systems have the fastest melt rates from cold charge to pouring temperature and melt more pounds per kWh and kVA for lower melting costs and greater productivity.

Water Systems with Closed-Circuit Industrial Coolers have many advantages and are ideal for cooling in any climate for a wide variety of reasons.

The Inductotherm ARMS® (Automated Robotic Melt Shop) System is a patented concept that uses a robot to perform the hazardous operations that would otherwise be handled by a furnace operator, allowing the melt deck worker to be relocated to the control room.

Take control of your foundry or melt shop with our automated melting control systems that monitor and control the melt, diagnose faults, optimize power usage, minimize power charges and perform a variety of tasks to provide more control for complete melt shop control.