Cradle to Gate
Identity ID
c5180e9f-ae8f-4e47-9f93-b8b857d25b9a
Materials
Associated ID
f48fc3c2-a37e-4cd5-8247-45748209235c
Included activities starts
Included activities ends
Description
This dataset represents the life cycle inventory (cradle-to-gate) of middlings produced from coal preparation, 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 commuting and daily office operations during the coal washing process. 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", the dataset was compiled from multiple data sources and is representative of the average production level in Shanxi.
Activity Description
Coal preparation refers to the process of removing shale and other impurities from coal through various physical, chemical, or physicochemical methods to improve coal quality. The following is a detailed description and introduction of the entire coal preparation production process in China:
1. Raw Coal Preparation
Coal crushing and screening:
Raw coal is first crushed into particles suitable for coal preparation by crushers. The crushed coal then enters screening equipment for particle size classification, directing coal of different sizes to corresponding coal preparation equipment.
The screening process can be divided into several stages to ensure that coal of different sizes receives optimal treatment. Pre-selection
Impurity removal equipment:
Before formal coal beneficiation, magnetic separators, iron removers, and other equipment are used to remove metal impurities and large gangue pieces from raw coal.
The goal of the pre-selection stage is to reduce the impurity content entering subsequent coal beneficiation processes and to improve coal beneficiation efficiency.
3. Jig Coal Washing
Jigging Separation:
Coarse coal is separated using a jigging machine. The jig utilizes the pulsating action of water to stratify coal and impurities based on density. The lower-density clean coal rises to the upper layer, while higher-density gangue and impurities sink to the lower layer.
Coal enters the feed hopper of the jig and is mixed with water to form a slurry. Under the action of the jig, clean coal and impurities are stratified. The clean coal is collected via an overflow chute or discharge device, while the impurities are discharged through the discharge outlet. Dense Medium Coal Preparation
Dense medium separation:
Medium-sized coal is separated using a dense medium separator. In a dense medium suspension, coal with lower density floats, while impurities with higher density sink, achieving separation between coal and impurities.
Magnetite powder or other dense medium materials are mixed with water to form a suspension of specified density. After separation, the dense medium suspension is processed through a magnetic separator to recover the magnetite powder for recycling.
5. Flotation Coal Preparation
Grinding:
Fine-sized coal must be further ground to achieve a particle size suitable for flotation (typically 0. particles smaller than 1 mm).
Froth flotation sorting:
The ground coal powder is mixed with water to form a slurry, into which flotation reagents (such as collectors, frothers, and modifiers) are added, and then fed into flotation cells. Through mechanical agitation and air injection, bubbles are generated. Coal particles attach to the bubbles and rise to the surface of the slurry, forming a froth layer. The froth layer is then collected to obtain high-purity clean coal. Coking coal processing
Dewatering:
After coal preparation processes such as jiggering, heavy medium separation, and flotation, the resulting clean coal contains a certain amount of moisture. It is therefore necessary to dewater the coal using dewatering equipment (e.g., dewatering screens, centrifuges, or filter presses) to reduce moisture content and improve the quality of the clean coal.
Storage and transportation:
The dewatered clean coal must be properly stored and transported. To prevent moisture absorption and spontaneous combustion during storage and transportation, protective measures should be implemented, such as storing the coal in coal sheds or enclosed stockyards. Tailings Management
Tailings Disposal:
Tailings (mainly gangue and impurities) generated during the coal beneficiation processes such as jigging, heavy medium separation, and flotation are discharged through discharge equipment and transported to the tailings management area.
Tailings Dewatering and Wastewater Treatment:
The moisture contained in the tailings must be further treated. After dewatering using thickeners or filters, solid tailings are either stored or subjected to further processing. Wastewater generated during the flotation process is treated for recycling or discharged in compliance with environmental regulations, thereby minimizing environmental pollution.
8. Environmental Protection and Safety Measures
Environmental Protection Measures:
Coal preparation plants should implement environmental protection measures such as dust control and wastewater treatment to minimize environmental impact. Treated wastewater can be reused or discharged in compliance with regulatory standards, thereby reducing water consumption.
Safety Measures:
Establish and enforce safety production regulations, conduct regular safety inspections and training, and equip facilities with protective devices and emergency response systems to ensure worker safety.
Process Description
Medium coal is a mixture of coal gangue and clean coal separated from raw coal, and is an intermediate product from coal washing with ash content between clean coal and gangue.
Time period
2022
2026
Geography
China,Shanxi
Geography comment
Forming Shanxi's average data through merging data from multiple sources.
Macroeconomic value
Business-as-Usual
Data validation
Yes
Technology
Current Technology
Technology comment
Not specified