Cradle to Gate
Identity ID
c5347b7c-7a3b-4dd0-9140-e8707b2faf51
Materials
Associated ID
fbeef16f-5d0e-4c99-9797-49af34c2f2ad
Included activities starts
Included activities ends
Description
This dataset represents the life cycle inventory of the process from heavy middlings coal beneficiation to the production of medium-sized thermal coal, covering all coal washing-related activities cradle-to-gate, but excluding external factors outside the coal preparation plant (such as raw coal mining, utilization of Clean coal, etc.), as well as direct or indirect greenhouse gas emissions resulting from employee commuting and daily office operations during the coal washing process. The dataset, based on national standards such as the "Cleaner Production Standard for the Coal Mining and Washing Industry" (HJ 446-2008) and the "Emission Standard of Pollutants for the Coal Industry," was developed by consolidating data from multiple sources and is representative of the average production level in Gansu.
Activity Description
This dataset describes heavy medium coal beneficiation, a method that uses a heavy medium suspension to separate coal from impurities. The specific process is as follows:
Coal crushing:
Raw coal is crushed by a crusher into particles suitable for washing, typically below 50 mm. The crushed coal then enters screening equipment for particle size classification.
Preparation of heavy medium suspension:
Magnetite powder or other heavy medium materials are mixed with water to prepare a heavy medium suspension of a specific density. The density of the suspension is adjusted according to the density difference between coal and impurities.
Coal separation:
The crushed coal enters the heavy medium separator. In the suspension, coal with lower density floats while impurities with higher density sink, enabling separation of coal and impurities. The separated light fraction (coal) and heavy fraction (impurities) are discharged through different outlets.
Recovery of dense medium:
The dense medium suspension after separation is processed through a magnetic separator to recover magnetite powder, which is then recycled. The recovered dense medium materials are returned to the preparation stage.
Dewatering:
The separated coal contains a certain amount of moisture and is treated by dewatering equipment such as dewatering screens and centrifuges to reduce moisture content and increase the calorific value of the coal.
Storage and transportation:
After dewatering, the coal is stored and transported. To prevent coal from moisture absorption and spontaneous combustion during storage and transportation, protective measures should be taken, such as using coal sheds or enclosed stockyards for storage.
Process Description
In Gansu Province, the main types of thermal coal are long-flame coal, weakly caking coal, non-caking coal, and anthracite, with coal quality characterized by ash content of 9.54–23.51%, volatile matter of 7.85–44.93%, total sulfur of 0.23–2.86%, and carbon content of 73.59–85. 78%, with a net calorific value on an as-received basis (Qnet,ar) of 5,696~7,548 kcal/kg. In bituminous coal, middlings are a product intermediate between clean coal and gangue. Their quality is inferior to clean coal, containing certain amounts of impurities such as ash and sulfur, but superior to gangue, retaining a certain level of calorific value. Middlings typically contain a relatively high proportion of ash and can be used in industrial boilers and similar applications where coal quality requirements are not particularly stringent.
Time period
2022
2026
Geography
China,Gansu
Geography comment
Gansu's average data is formed by merging data from multiple sources.
Macroeconomic value
Business-as-Usual
Data validation
Yes
Technology
Current Technology
Technology comment
Heavy middlings coal beneficiation is an effective coal cleaning method primarily used to improve coal quality. This method employs a liquid medium with a density between that of coal and gangue for separation. The separation media used include heavy liquids and suspensions. Currently, both domestically and internationally, suspensions prepared by mixing magnetite powder with water are widely used as the separation medium in coal beneficiation. Heavy middlings coal beneficiation involves several steps, including coal crushing, preparation of the heavy middlings suspension, coal separation, recovery of the heavy middlings, and dewatering processes.