Cradle to Gate
Identity ID
5c15ab2e-c480-41bf-a081-d729c872f39c
Materials
Associated ID
de94c9e2-b7a3-4dfe-863c-540adbf8727c
Included activities starts
Included activities ends
Description
This dataset represents the life cycle inventory (cradle-to-gate) of medium-sized coking coal produced through a combined process of heavy middlings separation and flotation coal preparation, covering all activities related to coal washing. However, it does not include conditions external to the coal preparation plant (such as raw coal mining, utilization of Clean coal, etc.), nor direct or indirect greenhouse gas emissions resulting from employee commuting and daily office operations during the coal preparation process. Based on national standards such as 'Cleaner Production Standard for the Coal Mining and Selection Industry' (HJ 446-2008) and 'Emission Standards of Pollutants for the Coal Industry,' this dataset was developed by synthesizing data from multiple sources and is representative of the average production level in Shanxi.
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
Coking coal in Shanxi Province is widely distributed in the Taiyuan Formation and Shanxi Formation. The Taiyuan Formation includes gas coal, fat coal, coking coal, lean coal, and gas-fat coal, while the Shanxi Formation includes gas coal, fat coal, coking coal, and lean coal. The raw coal ash content of the Taiyuan Formation ranges from 6.95% to 37.97%, volatile matter from 9.6% to 41.01%, maximum thickness of the plastic layer from 0 to 40 mm, total sulfur from 0.68% to 5.97%, and Qnet,ar (gross calorific value on an as-received basis) from 7712 to 9078 kcal/kg. The raw coal ash content of the Shanxi Formation ranges from 16.53% to 34.33%, and volatile matter from 13% to 40%. 0.3%, with a maximum thickness of the vitrinite layer ranging from 0 to 75 mm, and a net calorific value on an as-received basis (Qnet,ar) of 7,400–8,660 kcal/kg. The middlings in coking coal are intermediate products between clean coal and gangue. The middlings in coking coal generally have relatively high ash content, possibly reaching around 25%–40%. Their caking and coking properties are inferior to those of Coking clean coal. Middlings from coking coal are generally unsuitable for the production of high-quality coke, as their higher impurity content can negatively affect coke quality indicators such as strength and pore structure. However, in some applications with slightly lower coke quality requirements or after special treatment, coking Middlingss can be partially used to produce coke, or utilized for other industrial combustion purposes, such as being used as a fuel in industrial boilers. However, the impacts of harmful components such as sulfur content on the environment and equipment must be considered.
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
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.