With cement production being such an energy-hungry process, it is little surprise that Chinese authorities want the industry to do more to make alternative fuel a permanent part of its processes. The move seems well timed as cement plants around the world increasingly introduce co-processing to their incineration processes.
Co-processing refers to the use of waste materials in industrial processes or other types of combustion plants. On the one side, the idea behind it is substituting primary fuels, such as coal, petroleum and gas, with waste. On the other, it involves substituting natural raw materials used in the production process with waste materials.
In China, with its massive build-up in urban waste, there are multiple advantages to introducing co-processing to cement production: helping to manage the waste burden on society, reducing the dependency on fossil fuels, and minimising the impact of cement plants on the environment. But although the benefits are clear, actually making co-processing work requires a quite different approach in China than in other countries.
A different kind of waste
After working in the cement industry for 33 years, Zhou Lun, General Manager of Cement Operations for FLSmidth China has followed closely the development of co-processing in industrial processes. He explains that the composition of waste for burning in China is not the same as what people in other regions refer to as refuse derived fuel (RDF), which consists mainly of plastics and biodegradable waste produced with waste converter technology.
“Whereas co-processing in most countries involves traditional RDFs as alternative fuels, the urban waste to be co-processed in China contains a high proportion of water and non-combustibles.
In the Chinese cement industry, co-processing is simply about disposing of raw municipal waste and other difficult materials in a safe and harmless way. But this is difficult, because it typically emits a relatively low amount of heat. In cement kilns, this could have a negative impact on production. So to make use of every calorie from the waste while maintaining stable cement process and quality, a special type of incineration technology is required. Currently, producers do not have much choice when it comes to workable solutions.”
In addition to the environmental advantages of co-processing, there are significant business upsides for cement producers, particularly in the light of China’s big cement surplus. Zhou Lun says that China’s national capacity reached 3.5 billion tonnes in 2015 – more than half of the world’s capacity – yet domestic consumption was only 2.2 billion tonnes.
Competition is very tough and it’s unlikely to change in the near future. Cement producers need to think about alternative business models, and burning garbage is one way of diversifying
It is especially important for cement plants close to cities, where most people see cement plants as polluters. For example, if plants close to Beijing didn’t burn urban waste, they may be faced with immediate closure by local authorities. Companies are being offered subsidies to burn urban waste, so it actually gives them a valid reason to stay in business, even if cement production has become less profitable.
There have been some concerns that the use of waste affects clinker quality, but the effects are negligible, claims Zhou Lun:
“In fact, there is actually an environmental benefit, which also reflects the principle of co-processing. The ash residue, which may contain heavy metals, can now be absorbed and solidified in the clinker minerals, so it won’t be a danger to the environment. Another beauty is that due to the sufficient high temperature and long retention time in the host system, the formation of dioxin is decisively suppressed to the level better than any current norms and standards require.”
And it is these environmental benefits that are most likely to win over the public, which is sceptical at best about waste incinerators. In addition to the financial benefits through government subsidies, there are clear opportunities for producers to boost their public image by showing that co-processing helps to meet their social responsibilities. Inevitably, one of the big concerns is gaseous and dust emissions.
“The incineration technology must at least minimise or, even better, eradicate emissions of dioxins and other harmful substances,” says Zhou Lun.
“We must look to the highest international standards, especially if cement plants are to gain the confidence of the general public.”