Si 2020 – improved production process

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The basic principles of silicon production are around 100 years old. A number of different improvement measures have resulted in a considerably better process. In 2011 Elkem decided to start a research programme that would carry out a thorough review of each step of the production process to examine the residual potential that remains with regard to better material yield and reduced losses, lower emissions, and more efficient energy consumption.

The Si 2020 research programme is a ten-year research project in Elkem that aims to improve the entire production process for silicon (Si) and ferrosilicon (FeSi), from the choice and supply of various raw materials to casting metal and the finished silicon product. Si 2020 has identified a huge potential. The goal is to find and develop new technology and production methods that can increase the silicon yield in the processes, from quartz to finished product, while lowering energy consumption and emissions and making the processes cleaner and safer for employees.

The Si 2020 programme consists of various sub-projects that focus on selected steps in the production, as shown in the figure below. Between 2012 and today, research projects have been started in the following areas:

  1. Improving Elkem’s understanding of the properties of raw materials and how these affect the process.
  2. Improving Elkem’s understanding of fundamental aspects of designing and operating smelting furnaces.
  3. Developing new methods of monitoring furnace surfaces.
  4. More efficient refining of silicon and ferrosilicon.
  5. Investigating how thin casting silicon can reduce losses and improve product quality.

Possible improvements in each step of the production process

Broad research

The goal of the Si 2020 programme has been to establish research projects at universities and university colleges that are directly linked to the internal projects and are supported by the Research Council of Norway and the EU. The following research projects have been established as part of the Si 2020 programme:

  • ESiP’s goal is to improve energy consumption in the furnace process by developing a new operation support system that utilizes new measurements, new understanding, and new mathematical models of what is happening inside the smelting furnaces. Other participants: Cybernetica and SINTEF.
  • BiOCarb+ is tasked with developing new knowledge about production and the use of biomass as a reduction material in FeSi and Si processes. Other participants: SINTEF ER, NTNU, NFLI, Eyde-network and Norsk Biobrensel AS.
  • SiNG is looking into how natural gas can be used as a reduction material in FeSi and Si processes and studying chemical reaction patterns in smelting furnaces with the aim of increasing the extraction percentage of silicon by 5 per cent. Other participants: SINTEF and NTNU.
  • CoRReSi is developing a new concept for the refining process through actively controlling the temperature during the refining process and through basic research into the chemical reactions that take place in the metal ladle during the refining. Other participants: SINTEF, Teknova and KTH in Stockholm.
  • CorSiCa is tasked with developing mathematical models of how casting silicon and the subsequent cooling determines product quality and recommend equipment designs and operation methods to utilize this new knowledge in operations. Other participants: SINTEF and Teknova.
  • ReCoBa is an EU project aimed at improving process control during refining and casting. The project has ten participants from a number of countries. Other industrial companies involved include BASF and Thyssen Krupp.

Improved energy efficiency

The ESiP (Energy efficient Silicon Production) research project consists of subprojects 1, 2 and 3 in Si 2020 and includes the development of methods for monitoring furnace surfaces, studies at SINTEF of material and energy flows in the furnace process, and mathematical modelling of the furnace process at Cybernetica. ESiP’s goal is to improve energy efficiency in silicon production through the use of a new operation sup- port system that will be developed on the basis of new measurements, new process understanding, and mathematical models. The project has received funding from the Research Council of Norway for 2013-2016.

Silicon is extracted from quartz. With the current methods of silicon production 80-85 per cent of the silicon is extracted. The goal of the ESiP research project is to increase the utilisation of the raw material by at least 5 per cent without increasing energy consumption. By man- aging the production processes better, Elkem can achieve energy savings of 200 GWh, if the method can be implemented throughout the group. The Si 2020 programme focuses on maximizing the silicon yield from raw materials to the finished marketable product.

Producing results

Elkem has already seen that Si 2020 has produced results. Findings from the ESiP project have already been used in the operation of the smelting furnaces.

  • Camera systems have been installed to monitor the furnace surfaces at two smelting plants. The new systems have proved important aids in managing the furnace.
  • New knowledge has been developed about how the material properties of the quartz raw material affect the furnace process. A new test and measurement programme for quality assuring quartz has been established based on this new knowledge.
  • The mathematical models for the furnace process and new process knowledge has been used to establish new, improved operating methods for a smelting furnace in one of the smelting plants. This has resulted in better operational stability and a very high silicon yield from this furnace.

Elkem University

The dissemination of new knowledge to the rest of the Elkem organisation is a priority task. The main channel for this is the Elkem University, where process engineers and other employees from Elkem’s melting plants take part in a one week ‘university’ with lectures on fundamental process knowledge at which the results from the Si 2020 projects are presented. The Si 2020 programme also offers shorter courses in specific fields. The Si 2020 programme also includes doctoral programmes at NTNU and KTH.