Cradle to Gate
Identity ID
4c749028-3453-49b5-9d37-debd88044e6a
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 clean coal from dense medium separation, covering all activities related to coal washing, but excluding external conditions such as raw coal mining, use of clean coal, employee commuting, and emissions associated with daily office operations. The dataset, compiled from multiple data sources in accordance with national standards such as the "Clean Production Standard for the Coal Mining and Washing Industry" (HJ 446-2008) and the "Emission Standards for Pollutants from the Coal Industry", is representative of the average production level in Shanxi.
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
Shanxi Province's steam coal is widely distributed in the Taiyuan Formation, Shanxi Formation, and Datong Formation. The Taiyuan and Shanxi Formations are primarily anthracite and lean coal, while the Datong Formation is mainly weakly caking coal. The Taiyuan Formation has ash content ranging from 12.62% to 28.52%, volatile matter from 6.5% to 14.79%, maximum thickness of vitrinite layer at 0 mm, total sulfur in raw coal from 1.2% to 6.65%, and net calorific value on an as-received basis (Qnet,ar) between 8136 and 8749 kcal/kg. The Shanxi Formation has ash content ranging from 8% to 35%, volatile matter in raw coal from 6.4% to 16.6%, maximum thickness of vitrinite layer from 0 to 12 mm, and total sulfur in raw coal from 0.2% to. 92%, with Qnet,ar (as-received net calorific value) ranging from 8350 to 8577 kcal/kg. Datong coal group: raw coal ash content 8.56–16.13%, refined coal volatile matter 29.73–35.52%, maximum thickness of the vitrinite layer 0 mm, total sulfur content in raw coal 0.49–1. 93%, with a net calorific value (Qnet,ar) of 7705~7946 kcal/kg. Among thermal coal, middlings are a byproduct intermediate between clean coal and gangue. Their quality is inferior to clean coal, containing certain amounts of impurities such as ash and sulfur, yet better than gangue, still possessing a certain level of calorific value. Middlings typically have a relatively high ash content and can be used in industrial boilers and other applications where coal quality requirements are not particularly high.
Time period
2022
2026
Geography
China,Shanxi
Geography comment
Forming Shanxi's average data through the integration of 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.