Cradle to Gate
Identity ID
122c740d-8f7a-4c82-a9f6-50e257e62690
Materials
Associated ID
fbeef16f-5d0e-4c99-9797-49af34c2f2ad
Included activities starts
Included activities ends
Description
This dataset represents a life cycle inventory (cradle-to-gate) for the production of middlings from dense medium separation to the output of thermal coal, covering all activities related to coal washing, but excluding external conditions beyond the coal preparation plant (e.g., raw coal mining, utilization of Clean coal), as well as direct or indirect greenhouse gas emissions from personnel travel 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," is compiled from data from multiple sources and is representative of average production levels in Shandong.
Activity Description
This dataset describes heavy medium coal preparation, a method that utilizes a heavy medium suspension to separate coal from impurities, with the specific process as follows:
Coal crushing:
Raw coal is crushed by a crusher into particles suitable for washing, generally 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 create 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 is fed into a heavy medium separator. In the suspension, coal with lower density floats, while impurities with higher density sink, achieving separation of coal and impurities.
After separation, the light product (coal) and heavy product (impurities) are discharged through different outlets.
Heavy medium recovery:
After separation, the heavy medium suspension passes through a magnetic separator to recover magnetite powder, which is reused in a closed loop. The recovered heavy medium material is returned to the preparation stage.
Dewatering:
The separated coal contains certain moisture, which is removed using dewatering screens, centrifuges, and other equipment 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 implemented, such as storing coal in coal sheds or enclosed stockyards.
Process Description
Shandong Province's power coal is mainly lignite. After coal washing, washed lump coal has a total moisture content of less than 20%, ash content of 12–16%, volatile matter of 43–44%, total sulfur of 0.5%, and a net calorific value on an as-received basis (Qnet,ar) of 4128–5520 kcal/kg; washed mixed coal has a total moisture content of less than 21%, ash content of 14–28%, volatile matter of 44–53%, and total sulfur of 0.6–0.9%. 8%, and the net calorific value on an as-received basis (Qnet,ar) ranges from 3514 to 5018 kcal/kg. Among thermal coal, middlings are a product intermediate between clean coal and gangue. Their quality is inferior to clean coal, containing certain amounts of ash, sulfur, and other impurities, yet better than gangue, still possessing a certain level of calorific value. Middlings typically contain a relatively high proportion of ash and can be used in industrial boilers and other applications where coal quality requirements are not particularly stringent.
Time period
2022
2026
Geography
China,Shandong
Geography comment
Forming Shandong's average data through 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.