Cradle to Gate
Identity ID
5b2c1472-677c-413a-b766-9770de6c6c25
Materials
Associated ID
78b6211d-17b0-47b8-9abe-7616b967dfcd
Included activities starts
Included activities ends
Description
This dataset represents the life cycle inventory (cradle-to-gate) of coal preparation involving a combination of dense medium separation, jigging, and flotation processes, up to the production of clean coal and medium-coal. It covers all activities related to coal washing, but excludes external conditions beyond the coal preparation plant (such as raw coal mining and end-use 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 is based on national standards including the "Clean Production Standard for the Coal Mining and Washing Industry" (HJ 446-2008) and the "Emission Standards for Pollutants from Coal Industry", and has been compiled from multiple data sources to represent the average production level in China.
Activity Description
This dataset describes dense medium coal beneficiation, jig coal beneficiation, and flotation coal beneficiation as three efficient coal beneficiation processes. Their combined use can better handle coal of different particle sizes and qualities, improving coal separation efficiency. Below is a detailed description and introduction of the entire production process for the combined dense medium, jig, and flotation coal beneficiation:
1. Raw Coal Preparation
Coal Crushing and Screening:
Raw coal is crushed by crushers into particles suitable for dense medium, jig, and flotation coal beneficiation. Generally, coarse-sized coal (>50 mm) undergoes jig separation, medium-sized coal (0.5-50 mm) undergoes dense medium coal beneficiation, and fine-sized coal (<0. coal with a size of 5 mm) for flotation separation. The crushed coal is classified by size using screening equipment, and coal of different sizes is sent to 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:
Medium-sized coal particles are separated using a heavy medium separator. In the heavy medium suspension, coal with lower density floats, while impurities with higher density sink, thus achieving separation of coal and impurities.
The light product (clean coal) and heavy product (impurities) after separation are discharged through different outlets.
Recovery of heavy medium:
The heavy medium suspension after separation is processed through a magnetic separator to recover the magnetite powder for recycling. The recycled medium material is reintroduced into the preparation stage.
3. Jigging Separation
Jig Preparation:
Coarse coal is separated using a jig, which utilizes pulsating water to stratify coal and impurities based on density. The lighter clean coal rises to the upper layer, while the denser gangue and impurities sink 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 the discharge outlet.
4. Flotation separation
Grinding:
Medium and fine coal particles need further grinding before entering the flotation machine to achieve a particle size suitable for flotation (typically below 0.1 mm).
Flotation reagent addition:
The ground coal powder is mixed with water to form a slurry. After adding flotation reagents (such as collectors, frothers, and modifiers), the slurry is fed into the flotation cell.
Flotation process:
In 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. Coking coal processing
Dewatering:
After coal preparation processes such as dense medium separation, jigging, and froth flotation, the clean coal contains a certain amount of moisture and requires dewatering treatment using dewatering equipment (e.g., dewatering screens, centrifuges, or filter presses) to reduce moisture content and improve coal quality.
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. Tailings Management
Tailings Discharge:
Tailings generated during the coal preparation processes of heavy medium separation, jigging, and froth flotation—primarily composed of gangue and impurities—are discharged via discharge units and transported to the tailings management area.
Tailings Dewatering and Wastewater Treatment:
The water contained in the tailings must be further processed. 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 standards, thereby minimizing environmental pollution.
Process Description
Cleansed coal refers to high-quality coal that has been processed in a coal preparation plant, reducing ash and sulfur content and removing certain impurities, making it suitable for specific applications.
Time period
2022
2026
Geography
China
Geography comment
Forming China's average data through merging multiple provincial datasets
Macroeconomic value
Business-as-Usual
Data validation
Yes
Technology
Current Technology
Technology comment
The combined coal preparation process using dense medium separation, jigging, and flotation is an efficient and flexible coal beneficiation technology. By integrating dense medium separation, jigging, and flotation, it can effectively process coal of different particle sizes and qualities. The production process includes coal crushing and screening, dense medium separation, jigging separation, flotation separation, clean coal treatment, and tailings management. This technology significantly enhances coal purity and utilization efficiency, offering high processing capacity, high separation efficiency, and environmental friendliness, making it widely used in coal preparation plants.