Cradle to Gate
Identity ID
830eee49-3571-4f86-8607-5ba90bc9e63c
Materials
Associated ID
d4faac86-4522-40c3-823b-29150b4f1222
Included activities starts
Included activities ends
Description
This dataset represents the life cycle inventory (cradle-to-gate) for the process starting from jig coal beneficiation to the production of middlings as thermal coal, covering all activities associated with coal washing, but excluding conditions external to the coal preparation plant (e.g., raw coal mining, utilization of Clean coal), as well as direct or indirect greenhouse gas emissions arising from employee commuting and daily office operations during the coal washing process. Based on national standards such as "Cleaner Production Standard for Coal Mining and Preparation Industry" (HJ 446-2008) and "Emission Standards of Pollutants for the Coal Industry", the dataset was compiled from multiple data sources and is representative of the average production level in Shaanxi.
Activity Description
This dataset describes jig coal washing, a physical coal beneficiation method that separates coal from impurities based on differences in their settling velocities in water. It is primarily used for processing lump coal and medium-sized coal particles. The specific process is as follows:
1. Raw coal preparation
Coal crushing and screening:
Raw coal is crushed by a crusher into particles suitable for jig coal washing, typically ranging in size from 0.5 mm to 50 mm. The crushed coal then enters screening equipment for size classification; appropriately sized coal is fed into the jig, while unsuitable particle sizes are directed to corresponding processing equipment.
2. Jigging Separation
Jig Machine Preparation:
The jig machine is the core equipment for jig coal washing. It periodically pulses water upward through the bed layer, enabling separation of coal and impurities based on their different settling velocities in water. An appropriate jig machine model is selected according to the particle size of the coal being processed.
Ore Feed:
The screened coal is uniformly fed into the feed hopper of the jig machine and mixed with water to form a slurry.
Separation Process:
Using the pulsating action of water, the jig machine stratifies the ore particles in the bed layer according to density. Low-density clean coal rises to the upper layer, while high-density gangue and impurities sink to the lower layer. A discharge device is installed at the bottom of the jig machine to remove gangue and impurities from the lower layer, while the cleaned coal from the upper layer is collected through an overflow chute or other discharge devices.
3. Cleaned Coal Processing
Dewatering:
The cleaned coal after jigging contains a certain amount of moisture. Dewatering equipment (such as dewatering screens, centrifuges, or filter presses) is used to reduce the moisture content and improve the quality of the cleaned coal.
Storage and Transportation:
The dewatered cleaned coal is stored and transported. To prevent moisture absorption and spontaneous combustion during storage and transportation, protective measures must be implemented, such as storing in coal sheds or enclosed stockyards.
4. Tailings Management
Tailings Disposal:
The tailings (primarily gangue and impurities) generated during the jigger coal cleaning process are discharged through discharge equipment to the tailings management area.
Tailings Dewatering and Wastewater Treatment:
The moisture contained in the tailings requires further treatment. After dewatering using thickeners or filters, solid tailings are either stored or subjected to further processing. The wastewater generated during the jigger coal cleaning process is treated and then either recycled or discharged in compliance with environmental standards to reduce environmental pollution.
Process Description
The main types of coal in Shaanxi Province are long-flame coal, non-caking coal, weakly caking coal, lean coal, and anthracite coal, with coal quality parameters as follows: raw coal ash content 6.12–42.16%, volatile matter 4.68–45.4%, total sulfur 0.23–5.33%, and gross as-received low heating value (Qnet,ar) 5111–7874 kcal/kg. After coal preparation (washing), the clean coal has ash content of 2.84–13.54%, volatile matter 7.06–44.61%, and carbon content 76.84–95. 78%, with a net calorific value on an as-received basis (Qnet,ar) ranging from 7324 to 8694 kcal/kg. In thermal 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, yet superior to 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 high.
Time period
2022
2026
Geography
China,Shaanxi
Geography comment
Formed Shaanxi's average data through merging data from multiple sources.
Macroeconomic value
Business-as-Usual
Data validation
Yes
Technology
Current Technology
Technology comment
Jig coal washing is an efficient and environmentally friendly physical coal beneficiation method that separates coal from impurities based on their different settling velocities in water. The production process of jig coal washing includes coal crushing and screening, jig separation, clean coal processing, and tailings management. This technology significantly enhances coal purity and utilization efficiency, featuring high processing capacity, low energy consumption, and environmental compatibility. It is widely applied in the beneficiation of lump coal and medium-sized coal particles.