Cradle to Gate
Identity ID
f261c3da-3ea2-40e2-b4d5-7295fb9ca60f
Materials
Associated ID
a726734c-c986-4eb1-a1bb-c840f23f4539
Included activities starts
Included activities ends
Description
This dataset represents the life cycle inventory (cradle-to-gate) of middlings produced through a combined heavy middlings separation and flotation coal washing process, covering all coal washing-related activities. However, it excludes conditions external to the coal washing plant (e.g., raw coal mining, utilization of Clean coal), as well as direct or indirect greenhouse gas emissions from staff 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", this dataset is synthesized from multiple data sources and is representative of the average production level in China.
Activity Description
This dataset describes heavy medium coal preparation and flotation coal preparation as two highly efficient coal preparation processes. By combining these methods, coal of different particle sizes and qualities can be processed more effectively, improving coal separation efficiency. Below is a detailed description and introduction of the entire production process of the combined heavy medium and flotation coal preparation:
1. Raw Coal Preparation
Coal Crushing and Screening:
Raw coal is first crushed by crushers into particles suitable for heavy medium and flotation coal preparation. Generally, coarse-sized coal (0.5-50 mm) will undergo heavy medium coal preparation, while fine-sized coal (0. Coal smaller than 5 mm is subjected to flotation separation. The crushed coal is classified by size using screening equipment, and coal of different sizes is sent to the corresponding coal preparation equipment.
2. Heavy Medium Separation
Preparation of Heavy Medium Suspension:
Mix magnetite powder or other heavy medium materials with water to prepare 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:
Coarse coal is separated using a heavy medium separator. In the heavy medium suspension, coal with lower density floats, while impurities with higher density sink, achieving separation of coal and impurities.
The separated light product (clean coal) and heavy product (impurities) are discharged through different outlets.
Heavy Medium Recovery:
The heavy medium suspension after separation is processed through a magnetic separator to recover magnetite powder for recycling and reuse. The recycled medium material is reintroduced into the preparation stage.
3. Flotation Separation
Grinding:
Before entering the flotation machine, medium-sized and fine coal particles need to be further ground to achieve a size suitable for flotation (typically 0. Less than 1 mm).
Flotation Reagent Addition:
The finely ground coal powder is mixed with water to form a slurry, and flotation reagents (such as collectors, frothers, and modifiers) are added before being fed into the flotation cell.
Flotation Process:
Inside the flotation cell, bubbles are generated through mechanical agitation and air injection. Coal particles attach to the bubbles and rise to the surface of the slurry, forming a froth layer. This froth layer is collected to obtain high-purity clean coal.
4. Clean coal processing
Dewatering:
After heavy medium coal preparation and flotation coal preparation, the clean coal 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 sealed stockyards. Tailings Management
Tailings Discharge:
The tailings generated during the heavy medium separation and flotation 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 treatment. After dewatering using thickeners or filters, the solid tailings are stored or subjected to further processing. The wastewater generated during the flotation process is treated for recycling or discharged in compliance with environmental standards, thereby minimizing 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
The combined coal preparation process of dense medium separation and flotation is an efficient and flexible coal washing technology. By integrating dense medium separation and flotation, it can effectively process coal of different particle sizes and qualities. The production process includes coal crushing and screening, dense medium separation, flotation separation, clean coal treatment, and tailings management. 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.