Cradle to Gate
Identity ID
d05e8a2e-e1d0-49a6-9b78-dabad80c6c2b
Materials
Associated ID
ced037c8-fddd-42dd-a988-5c8ae2ff91d2
Included activities starts
Included activities ends
Description
This dataset represents a life cycle inventory (cradle-to-gate) for the process starting from jig coal beneficiation to the production of coking middlings, covering all activities related to coal washing, but excluding situations external to the coal preparation plant (e.g., raw coal mining, utilization of Clean coal), as well as direct or indirect greenhouse gas emissions from employee commuting and daily office operations during the coal washing process. The dataset, developed by consolidating data from multiple sources, complies with Chinese national standards such as "Clean Production Standard for the Coal Mining and Washing Industry" (HJ 446-2008) and "Emission Standards for Pollutants from the Coal Industry", and is representative of the average production level in China.
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
Coking coal is a type of coal used for producing high-quality coke in coking processes, and its quality and properties directly affect the coking process and the quality of the resulting coke. The middlings of coking coal are intermediate products between clean coal and gangue. The ash content of coking Middlingss is relatively high, possibly reaching about 25%–40%. Its caking and coking properties are inferior to those of Coking clean coal. Coking Middlingss are generally not suitable for the production of high-quality coke, as their higher impurity content can negatively affect quality indicators such as coke strength and pore structure. However, in some applications where coke quality requirements are slightly lower, or after special treatment, coking Middlingss can be partially utilized for coke production or used for other industrial combustion purposes, such as a fuel for industrial boilers. However, the impact of harmful components such as sulfur content on the environment and equipment must be considered.
Time period
2022
2026
Geography
China
Geography comment
Forming China'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.