Cradle to Gate
Identity ID
63894ddf-0798-4924-aa6e-7fc012ab7da8
Materials
Associated ID
be9c8da4-3045-4adc-81f8-98d2d832eb83
Included activities starts
Included activities ends
Description
This dataset represents the life cycle inventory (cradle-to-gate) for the production of middlings coal from jigging and dense medium separation coal preparation, covering all activities related to coal washing, but excluding conditions external to the coal preparation plant (such as raw coal mining, utilization of Clean coal, etc.), as well as direct or indirect greenhouse gas emissions from personnel commuting and daily office operations during the coal washing process. The dataset, based on national standards such as "Cleaner Production Standard for the Coal Mining and Washing Industry" (HJ 446-2008) and "Emission Standards of Pollutants for the Coal Industry", is compiled from data of multiple sources and represents the average production level in China.
Activity Description
This dataset describes the combined jigging and heavy medium coal washing process, which integrates both jigging coal washing and heavy medium coal washing methods. It is primarily used for processing coal of different particle sizes and qualities to achieve optimal separation efficiency. Below is a detailed description and introduction of the entire production process of the combined jigging and heavy medium coal washing:
1. Raw Coal Preparation
Coal Crushing and Screening:
Raw coal is first crushed by crushers into particles suitable for jigging and heavy medium coal washing. Generally, coarse-sized coal (above 50 mm) undergoes jigging separation, while medium-sized coal (0. Coal with a size range of 5-50 mm undergoes dense medium coal washing. The crushed coal is classified by particle size using screening equipment, and coal of different sizes is directed to the corresponding coal preparation equipment. 2. Jigging Separation
Jig Preparation:
Coarse coal is separated through a jig. The jig utilizes the pulsating action of water to stratify coal and impurities based on density. The lighter clean coal rises to the upper layer, while the denser gangue and impurities settle to the lower layer.
Separation Process:
Coal enters the feed hopper of the jig and mixes with water to form a slurry. Under the action of the jig, the clean coal and impurities are stratified. The clean coal is collected via an overflow chute or discharge device, while the impurities are discharged through a discharge outlet.
3. Dense medium separation
Preparation of dense medium suspension:
Mix magnetite powder or other dense medium materials with water to create a dense medium suspension of a specific density. The density of the suspension is adjusted according to the density difference between coal and impurities.
Coal separation:
Medium-sized coal particles are separated using a dense medium separator. In the dense medium suspension, coal with lower density floats, while impurities with higher density sink, thereby achieving separation of coal and impurities.
The light product (clean coal) and heavy product (impurities) after separation are discharged through different outlets.
Recovery of dense medium:
The dense medium suspension after separation is processed through a magnetic separator to recover the magnetite powder for recycling and reuse. The recycled medium material is reintroduced into the preparation process.
4. Clean Coal Processing
Dewatering:
Clean coal obtained from jig coal washing or dense medium coal washing contains a certain amount of moisture. It needs to be dewatered using dewatering equipment (such as dewatering screens, centrifuges, or filter presses) to reduce moisture content and improve the quality of clean coal.
Storage and Transportation:
The dewatered clean coal is stored and transported. To prevent moisture absorption and spontaneous combustion during storage and transportation, protective measures should be implemented, such as storing in coal sheds or enclosed stockyards.
5. Tailings Management
Tailings Discharge:
Tailings generated during jigger and dense medium coal preparation processes (mainly gangue and impurities) are discharged via discharge equipment and transported to the tailings management area.
Tailings Dewatering and Wastewater Treatment:
The moisture contained in the tailings requires further processing. After dewatering by thickeners or filters, solid tailings are stored or subjected to further treatment. Wastewater generated during dense medium coal preparation is treated for recycling or for discharge in compliance with environmental standards, thereby reducing environmental pollution.
Process Description
Thermal coal refers to coal used as a power source. In a narrow sense, it specifically refers to coal used for thermal power generation. Broadly speaking, any coal used for generating power—such as for electricity generation, locomotive propulsion, or boiler combustion—is classified as thermal coal. Among thermal coal products, medium coal (zhongmei) is an intermediate material between clean coal and gangue. Its quality is inferior to clean coal, containing certain amounts of impurities such as ash and sulfur, but it is better than gangue and still possesses a certain level of calorific value. Medium coal typically contains a relatively high proportion of ash and can be used in industrial boilers where coal quality requirements are not particularly high.
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
jigging and dense medium integrated coal preparation is an efficient and flexible coal processing technology. By integrating jigging and heavy middlings separation methods, it can effectively handle coal of different particle sizes and qualities. The production process includes coal crushing and screening, jigging separation, heavy middlings separation, clean coal processing, and tailings treatment. This technology significantly improves coal purity and utilization efficiency, offering high processing capacity, high separation efficiency, and environmental friendliness, and is widely applied in coal preparation plants.