Next Steps are part of the Synergia™ Process, which is exclusive to CQI. To learn more about this process, please visit Synergia™.
Once the raw meal arrives at the pre-heating tower, new quality tests are conducted.
The pre-heating tower provides benefits. It saves considerable amounts of energy. CQI is the only cement plant in Quebec to have invested in this type of equipment.
At the pre-heating tower, a series of cyclones stacked on each other transfer the energy between the hot gas and the raw meal. In under 30 seconds, the raw meal heats up from 90ºC to 900ºC, and calcination occurs during this short phase in the extended calcining furnace, where more than 60% of total heat energy is introduced from the process.
Heating the raw meal is an operation that requires much energy and fuel. Cement plants are generally run using fossil fuels, such as coal, oil, and natural gas.
To reduce its carbon footprint and the use of these fuels, CQI added a solid fuel reactor known as an Eco-Furnace. Through the hot gases produced from the remains in the cooking circuit, this reactor burns various solid materials, such as used tires. The heat generated through combustion in the reactor is introduced into the cooking circuit, thereby reducing the use of traditional fossil fuels.
As a pioneer in the cement industry, the company was the second in the world to acquire this type of equipment in 2005. Only six were in operation internationally in 2012. Subsequently, CQI has reduced its use of conventional fuels by converting materials that would otherwise end up in landfills into an alternative. Additionnally, our process conserves from dry material disposal sites and helps to reduce the environmental impact of industrial waste.
The energy generated by the eco-furnace is a clean technology whose efficiency has been certified through stringent and regular environmental tests.
Waste Material Recycling Centre
With the great success of the Eco-Furnace, CQI has continued developing its alternative fuels by making major investments to adapt the process for using waste materials and to equip the facility for receiving, processing, storing dosing, and combusting other non-recyclable materials that would otherwise end up in landfills. These facilities are grouped together under the name Waste Material Recycling Centre.
Here, wood, paper, cardboard and plastic waste (that are not kept by redemption centres) are processed. By transforming those products into a fuel format that has the power to fully heat the pyro-processing requirements, these materials further reduce the cement plant’s dependency on fossil fuels.
The Waste Material Recycling Centre includes a second line of preparation, which primarily processes post-construction asphalt shingles and treated wood pieces like old railway ties, and electric or telephone poles.
These facilities made the St-Basile cement plant the number one cement plant in North America when it comes to alternative fuels. Not only did the company find itself at an advantage to reduce its heat energy load, it also significantly reduced its carbon footprint. Indeed, the combustion of these alternative materials produces fewer greenhouse gases and other pollutants than that of traditional fossil fuels, which provide the company with an effective tool to help meet the targets for reduced emissions set by the Quebec government’s cap and trade system.
Recycling the energy of these materials directly benefits the company, since it means less waste is going to the landfills.
After calcination during the preheating step, the hot raw meal is put in the rotary kiln to become molten at a temperature around 1450ºC, using a powerful multi-fuel burner. At this step (liquid phase), the different oxides (lime, magnesium, aluminium, sulphur, iron) making up the raw material clump together in a crystal structure that differs from the original. The new material is then quickly cooled to achieve optimal crystal formation to produce very-high-quality cements.
At this stage, through the rotary effect of the kiln, the dust of the raw meal is liquefied and then cooled to form the little pellets known as clinker.
CQI’s rotary kiln (4.9m diameter and 42.7m long) has one of the lowest length/diameter ratios in the world. With its plant’s ultra-efficient pre-heating tower, there is no need for a large oven to produce the heat required for making the clinker. This way, energy losses are also prevented.
Clinker Cooler (T)
The molten clinker is quickly cooled in a cooler. The hot gases generated at this stage in the clinker cooler are recovered and re-used in the pyro-processing circuit, which, in turn, recovers heat, thereby improving the circuit’s energy efficiency.
Clinker samples are taken to ensure product quality control.