Dumping the waste – reusing ceramics
Ceramic tile manufacturer Johnson Tiles, Stoke on Trent, UK, has found ways to reduce water consumption and waste. Dr Roy Hodgkinson, Deputy Managing Director of the company, reports.
Johnson Tiles, based in Stoke on Trent, UK, introduced a formal waste management and recycling strategy in 1994. The company received The Queen’s Award for Environmental Achievement in 1997, became the first whiteware manufacturer to achieve ISO 14001 in 1998, and was included in The Sunday Times 50 Best Green Companies Awards this year.
With the manufacture of ceramic tiles relying heavily on non-renewable natural minerals and high energy use, the company continuously seeks ways to reduce energy costs and increase the amount of recyclable ceramic waste used in the production of tiles. A major initiative was the use of fired ceramic waste from other ceramic producers in north Staffordshire.
Today, 15 manufacturers deliver clean waste to the company where it is crushed and mixed with ball clays and other mineral components in a large ball mill, combined with water and ground to a fine slurry.
This saves over 20,000t of waste ceramics from landfill each year, and since the project commenced in 1994, approximately 280,000t has been diverted from landfill. The company adds at least 25% of recycled content to its tiles and this year has increased levels to 28.5%. It is believed that this is the only process of its type in the world and represents a significant cost saving for participating companies.
Following an investment of £35m in new production facilities at Stoke on Trent during 2001, further work was undertaken to consider recycling other materials and reducing energy use. The installation of a fast fire roller hearth kilns, together with other initiatives, has cut overall energy consumption by 25% per tonne of product produced. Unfortunately, this has not been enough to stave off the rising cost of gas, which has increased by over 135% in the last 12 months. These growing costs spurred Johnson Tiles to review all waste streams to ascertain whether changes in procedure or processes could create significant savings.
Wet to dry
One of the first non-energy savings was decreasing water use by recycling and switching to dry systems. With nearly half of the water used passing to the atmosphere during the drying process, the company has managed to collect and reuse 30,000m3 of waste water in a year. An added benefit was the virtual elimination of trade effluent emissions from raw material processing. Converting the tile edge scraping after in-line glazing from a wet system to a dry process has saved a further 2,100m3 of water per year.
A review of other waste materials led to reprocessing ceramic waste drawn into the dust extraction systems. Until recently this waste was sent to landfill but it is now dispersed in water and reintroduced into the manufacturing process. This saves nearly 2,000t of waste material each year and makes a corresponding saving of raw material costs.
Johnson Tiles discovered that simple changes often have a large effect. For years the company had dumped the plastic tubs and buckets used to hold glazes and pigments. These are now washed out and reused, making a five tonne reduction in the level of hazardous waste disposed of by the company each year.
This has resulted in several new actions being taken, including ensuring that product packaging is produced from recycled and recyclable materials. Where possible, the company purchases second hand pallets to eliminate reliance on virgin timber and has established company-wide collection points for metal, paper, cardboard and fluorescent tubes so that these materials can be sent for recycling.
Regular employee briefing sessions are held to reinforce the waste management and recycling policies and to keep employees informed about how successful the policies are.
Later this year, work will be undertaken on one of the kilns to fit equipment to recycle waste heat drawn from the kiln exit back to the front to limit energy use. Similar plans are being considered to use heat recovered from the kilns to augment other processes where heat is required.