Process information
| Key Data Set Information | |
| Location | SD-CN |
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| Use advice for data set | Users should note that calcium carbide slag production and pre-drying processes are based upon specific moisture content targets and energy requirements. When noting the LCA data, it is crucial to account for the environmental impacts appropriately across both products derived from calcium carbide hydrolysis, carbide slag and acetylene. Ensure that any adaptations of pre-drying processes or pre-heater stages are reflected in the adjustments to the environmental load and energy consumption. Model transport distances based on average values specific to the locality or the data provided. The life cycle inventory data sources should be acknowledged and applied consistently for comparative assessments. |
| Technical purpose of product or process | Calcium carbide slag is utilized as a substitute for limestone in the production of cement clinker, which is a core component in manufacturing concrete and other cement-based products. The industrial process includes the pre-drying of calcium carbide slag using coal-fired or kiln tail waste heat methods to achieve the required moisture content for cement production. |
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| General comment on data set | Calcium carbide sludge isthe co-product of acetylene generation from carbide in chemical industry, whosemain chemical composition is calcium hydrate. Before it is transported tocement industry, the moisture content of calcium carbide sludge produced fromthe acetylene generator is about 35%. However, it still can’ t meet therequirement of cement production; therefore, it needs further pre-drying tomake sure the moisture content of calcium carbide sludge reduce to 15%.Coal-fired pre-drying process. Many cement industries use 5-stage pre-heater when they produce cement clinker, and the temperature of kiln tail waste gas is about 320 °C. They use rotary dryer with a coal stove to pre-dry calcium carbide sludge, i.e., after calcium carbide sludge with the moisture content about 35% entering rotary dryer, the gas from coal combustion will contact with the surface of calcium carbide sludge, exchange heat until the moisture content becomes 15%. |
| Copyright | No |
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| Technology description including background system | Calcium carbide sludge is the co-product of acetylene generation from carbide in chemical industry, whose main chemical composition is calcium hydrate [2]. Before it is transported to cement industry, the moisture content of calcium carbide sludge produced from the acetylene generator is about 35%. However, it still can’ t meet the requirement of cement production; therefore, it needs further pre-drying to make sure the moisture content of calcium carbide sludge reduce to 15% [3]. There are two pre-drying processes currently.Coal-fired pre-drying process. Many cement industries use 5-stage pre-heater when they produce cement clinker, and the temperature of kiln tail waste gas is about 320 °C. They use rotary dryer with a coal stove to pre-dry calcium carbide sludge, i.e., after calcium carbide sludge with the moisture content about 35% entering rotary dryer, the gas from coal combustion will contact with the surface of calcium carbide sludge, exchange heat until the moisture content becomes 15%. Pre-drying process by waste heat from kiln tail. There is a process which is using cement kiln tail waste gas to pre-dry calcium carbide sludge to save coal consumed in this stage. One cement industry from Shandong consumes 1.2t calcium carbide sludge whose moisture content is 35% when produces 1t cement clinker. If calcium carbide sludge is pre-dried to 15%, it needs the temperature of gas from kiln tail about 700°C. Therefore, it can change the pre-heater from 5-stage to 2-stage so that make sure it has enough gas to pre-dry. However, with the decline of pre-heater stage, the clinker heat consumption will increase 1100KJ/kg, and the electricity reduced by 30%. |
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| Model description | This functional unit is set for 1 ton of cement clinker with a compressive strength of up to 42.5MPa.The life cycle of cement clinker production can be divided into six stages: mining, transportation, energy production, production of calcium carbide slag, processing of calcium carbide slag and production of cement clinker. |
Modelling and validation
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