Turning hazardous trash to useful resources

KUCHING: Cahya Mata Sarawak Bhd (CMS) is increasingly sourcing scheduled wastes generated by the various industries in Sarawak as alternative raw materials or fuels currently used in its group’s clinker, cement and concrete productions.

As Sarawak’s sole cement manufacturer, CMS said through the research and development (R&D) efforts of its cement division, it had made solid progress by way of managing scheduled wastes from industries within the state, especially those located in the Samalaju Industrial Park (SIP), Bintulu.

“The scheduled wastes or by-products generated by these industries provide us with alternative sources of materials that serve as substitutes for the typical raw materials or fuels currently used in the group’s clinker, cement and concrete production activities.

“They are also transformed into useful products with added performance attributes,” it added in the company’s Sustainability Report 2018 released this week.

The cement division’s R&D efforts focus on thee main areas – product development, alternative raw materials and alternative fuels.

The product development, explains CMS, involves the use of supplementary cementitious materials or additives, such as slag, silica fume, fly ash, limestone and other materials to replace clinker, resulting in new products with enhanced characteristics or which are used in other applications.

Clinker is a key material for cement manufacturing.

The alternative raw materials involves the use of wastes/by-products from other industries to replace the typical raw materials used in clinker, cement and concrete operations.

The alternative fuels involve the use of wastes/by-products with suitable calorific value to replace the traditional fuel used in clinker burning.

According to the report, silica fume is an ultrafine powder collected as a by-product of silicon and ferrosilicon alloy production supplied by OM Materials (Sarawak) Sdn Bhd and Pertama Ferroalloys Sdn Bhd which operates smelting plants in SIP.

 “By adding silica fume to produce blended Portland composite cement or by using it in concrete, this strengthens the performance of the cement and lends to higher durability.

“CMS Cement Industries Sdn Bhd has already received the relevant approvals from the Department of Environment (DOE) and conducted several plant trials in relation to the use of silica fume.”

Since 2015, CMS Cement has been burning small quantities of shredded tyres bought from a local supplier to manufacture clinker.

This tyre-derived fuel (TDF), said the company, produces the same energy as petrol and approximately 25 percent more energy then sub-bituminous coal.

CMS Cement has been given the approval by DOE to proceed with the trial of 300 tonnes of TDF which it hopes would eventually lead to the commercial production of TDF.

Also used is furnace slag to partially replace clinker in the production of Portland cement.

“Furnace slag is one of the by-products from Malaysia Phosphate Additives (Sarawak ) Sdn Bhd which can be used to substitute clinker in cement production or as alternative raw material in clinker production.

“Laboratory tests on furnace slag are on-going and more samples are expected to be brought in from China for further testing,” said the report.

On the by-product silicon manganese from OM Sarawak and Pertama Ferroalloys, the report said it has the potential to be used as aggregate replacement in concrete.

“Preliminary tests done undertaken by CMS Concrete Products Sdn Bhd show an increase in concrete strength with a 50 percent replacement of the coarse aggregate.

“Further testing is required to ensure the consistency of the quality produced.”

According to CMS, its construction materials & trading division’s slag waste trial at Sakura Ferroalloy plant in SIP was successful with the performance complying with the Public Works Department’s standard for road sub-base and road base as a quarry aggregate crusher run substitute.

However, it said, slag waste is still subject to DOE’s approval before it could be used on public roads.

 This year, CMS said it would close several deals with waste generators for scheduled wastes from several industries in Sarawak.

“We are pressing for SW427 (mineral sludges) supplies from EOX Linde Kota Kinabalu, BIG Miri and Bintulu, Piasau Gas Miri and Sibu Gas. The additional quantity per month will be around 200 to 300 tonnes.

“We are also continually looking into additional sources of sludge from within the industry.

“Following extensive research into using phosphogypsum (PG) as a replacement for limestone, our clinker plant has come to the conclusion that the waste material is viable as a material replacement.

“We have planned to purchase the waste material from an identified source.”

Added CMS: “The plant has also considered replacing its light fuel oil (LFO) with residual fuel oil. We are currently in discussions with Petronas and have sourced several recycled oil suppliers in Kuching area.

“The plant is also looking to substitute its use of limestone by up to 3 percent by replacing this with sludge, old kiln bricks and ash.”

The company is currently negotiating with DOE on getting scheduled waste transportation licences especially on the sea route.