Fly ash has been an ever-growing problem at coal-fired power plants. Thanks to environmental regulations, fly ash has to be stored, disposed of, or recycled into concrete. However, recycling fly ash requires it to reach certain standards, which can be hard to meet. ST Equipment & Technology LLC (STET) has found a way to use electrostatic separation equipment to solve or reduce the fly ash pollution problem.
When coal is burned, it produces a fine ash product. This ash is carried out of the boiler unit along with the flue gas combustion air, and captured by the power plants pollution control equipment. The ash collected in the flue gas is called fly ash. According to the American Coal Ash Association (ACAA) between the years 2000-2020 the industry produced around 1.1 billion short tons of fly ash.
In order to reduce the amount of waste being placed into landfills, fly ash has to be recycled into a usable product for cement production. However, if a certain amount of unburned carbon remains in the fly ash, it is not usable in the production of concrete.
Current ASTM standards mandate that fly ash used for concrete contain less than 6% residual carbon content. In practice, most end users have carbon specifications well below the 6% specification. This means that while fly ash is able to be used in concrete, the availability of quality fly ash that meets the carbon specification without processing is in limited supply.
In order to reduce the fly ash pollution problem, unburned carbon (coal char) must be removed from the fly ash to make it suitable to use in concrete. With the help of fly ash drying equipment, STET’s electrostatic beneficiation technology can do just that. STET’s triboelectric separator reduces the carbon content of fly ash and produces a low carbon fly ash that is suitable for cement replacement in ready-mix concrete.
In order for fly ash to be usable in cement, it has to measure a loss on ignition (LOI) of 6% or less by weight. Thankfully, STET has pioneered a process to remove carbon from fly ash. As described in our white paper titled 20 Years of Commercial Experience in Dry Triboelectrostatic Beneficiation of Fly Ash, “By controlling various process parameters, such as belt speed, feed point, and feed rate, the STET process produces low LOI fly ash at carbon contents of less than 1.5 to 4.5%”
Through the use of a triboelectric separator, STET can take a high carbon fly ash with 4% to over 25% LOI and turn it into a low LOI fly ash. This process effectively reduces the amount of carbon to a suitable amount.
Thanks to STET’s electrostatic separation equipment, pollution caused by fly ash disposal can be effectively reduced. In addition to reducing the disposal of fly ash, the separation process is environmentally friendly and produces no wastewater or air emissions.
Without the production of wastewater or air emissions, there are really only benefits to using electrostatic separation on carbon-dense fly ash. Now, you can effectively recycle fly ash into a suitable component of cement, without adversely affecting the environment.
Now that you have seen how a triboelectric separator can effectively reduce pollution caused by coal fly ash, you can see why investing in it would be beneficial. ST Equipment and Technologies LLC (STET) is an electrostatic separator company based out of Needham, MA.
We provide state-of-the-art mineral processing equipment, fly ash drying equipment, and electrostatic separation equipment to our customers all over the world. We are dedicated to helping our customers and the world we live in. Want to learn more? Contact us today!