Research Highlight: Synthesis of High Quality Zeolites from Coal Fly Ash

- Perth, Australia

Dr. Kevin Li (Gang Li), participated in CAA2017 on behalf of the Centre for Energy, School of Mechanical & Chemical Engineering at the University of Western Australia in Perth, Australia. Dr. Li, a returning speaker to Coal Ash Asia, focused his presentation on synthesizing zeolites and necessary related conditions. The below abstract is an overview of the research presented at the conference. For more of Dr. Li’s publications and research, please click the link at the bottom of the abstract.

Abstract: Coal fly ash is a hazardous industrial waste generated from coal combustion and has been considered as an appropriate raw material for zeolite synthesis. In this study, synthesis of a high-quality type A zeolites (471m /g surface area) from fly ash at high conversion rate (98.2% aluminium and 96.5% silicon) has been achieved via a two-step alkali fusion and hydrothermal procedure. Furthermore, in preparation for production in commercials scale, up scaling of the developed synthesis process has been undertaken by using 150L reactor. More importantly, we tracked the migration of elements and quantified their distribution from fly ash to product zeolites and waste water throughout the synthesis process. Metalloid elements including arsenic and selenium, and those with strong amphoteric properties such as molybdenum were found highly mobile and mostly collected in the waste water. In comparison, less than 20% of heavy metal elements of weak amphoteric nature including copper, chromium and lead originated from the fly ash went to the waste water; the rest of these three heavy metals along with almost all of the cadmium, iron and nickel were fixed into the product zeolites. Despite the accumulation of hazardous elements in product zeolites, none of them was leachable under various harsh conditions, ensuring safe applications of such zeolites.

If you are interested in attending Coal Ash Asia 2018 in Shuozhou, please click the "CAA2018" link to register, and our event team will assist you in finding the participation that's right for you.

China and Australian Coal Combustion Products Exchange: Millmerran Power Station and Independent Fly Ash Brokers

- Brisbane, Australia

A Chinese delegation including academics, power plant professionals and coal combustion product consumers traveled to Brisbane, Sydney, Melbourne and Cairns on a twelve day visit to Australia. The program, led by David Harris, Chairman of the Asian Coal Ash Association, and Bill Martin, senior partner with Coal Ash Solutions, included visits to key construction material and building material laboratories and production facilities.  The coal combustion products exchange took place from November 19th – 30th. 

The first stop on the tour was a visit to Millmerran Power Station and the co-located fly ash and bottom ash processing facility owned and operated by Independent Fly Ash Brokers. Millmerran Power Station, located just west of Brisbane, is a 1000-megawatt coal mine mouth power station, using pulverized coal and producing 3000 tons of coal ash per year. An introduction to the power station was provided by manager Joel Rickuss. The Chinese delegation observed an overview Millmerran, which is of one of the most cost efficient power stations in Australia. This is partly due to being located next to the coal mine. However, Millmerran also recycles the municipal waste water from the nearby city of Toowomba, piping the water to the station for use in their cooling system. The station does not use standard cooling towers, but a radiator system that proves to be very cost effective and resource efficient in a region of Australia where water conservation is a top priority. 

Bottom ash from the power station is being used for road base, improving the quality of roads for the coal mining operation. The fly ash is being collected by Independant Fly ash Brokers (IFB), a company jointly owned by three regional construction materials companies.  Due to the large distance from the markets, only 20-30% of the fly ash is being beneficially utilised. The rest is being used to backfill the coal mine.

The Chinese delegation noticed the difference in safety protocols and in the organization of the power station.

Independent Fly Ash Brokers is a joint venture between Wagners, Neilsens and Caldwells. IFB has a fly ash processing facility that is co-located with Millmerran. IFB pumps dry ash to their classifiers and silos pneumatically. The tour was given by Peter Dennis, IFB's operations manager.

The degree of automation at the IFB facility is impressive. After being pneumatically conveyed from the power station, fly ash is classified and then stored in hoppers, ready to discharge into pneumatic tanker trucks. Drivers of the tanker trucks pull into the loading bay, underneath the hopper outlet. The driver parks the truck and then goes to the operator deck to connect the discharge pipe from the hopper to the inlet on the truck storage tank. The hopper is on a gantry and - in the case of a double tanker truck - can be moved automatically by the truck driver from one tank to the next without moving the truck. The computer system indicates when the volume of ash has reached the tank capacity and automatically shuts off the discharge. 

All of this is done at a single loading control unit and is efficiently designed as trucks do not need to move from station to station. The whole loading process is operated by the truck driver, reducing labour costs and chances for human error. 

The delegation was very impressed by the degree of automation, cleanliness, organisation, and the factory design.

The next visit on our itinerary was to Wagner's Geoploymer. Wagner’s three trading divisions - Wagners Concrete, Quarries and Transport include cement, flyash and lime, reinforcing steel, on site concrete supply, contract crushing and bulk transport, as well as lightweight composite fibre products. Please view the next post in our post SACCP exchange series, for more information on that visit.