Cradle to Gate
Identity ID
f6213d40-4aeb-4c7e-aec5-264b6543c314
Materials
Associated ID
e9683e6c-5d68-4382-981f-bdbc59032c28
Included activities starts
Included activities ends
Description
This dataset represents the life cycle inventory (cradle-to-gate) of the entire process of coal preparation through combined jigs and flotation, resulting in the production of coking middlings. It covers all activities related to coal washing, but excludes conditions external to the coal preparation plant (such as raw coal mining and the use of Clean coal), as well as direct or indirect greenhouse gas emissions arising from personnel commuting and daily office operations during the coal washing process. The dataset, based on national standards such as "Cleaner Production Standard for Coal Mining and Washing Industry" (HJ 446-2008) and "Emission Standards of Pollutants for Coal Industry," was compiled from multiple data sources and is representative of the average production level in China.
Activity Description
This dataset describes combined jigging and froth flotation coal preparation, a process that integrates both jigging and froth flotation methods, primarily used for treating coals of different sizes and qualities to achieve optimal separation efficiency. Below is a detailed description and introduction of the entire production process of combined jigging and flotation coal preparation:
1. Raw Coal Preparation
Coal Crushing and Screening:
Raw coal is first crushed by crushers into particles suitable for jigging and flotation. Generally, coarse-sized coal (above 50 mm) will undergo jigging separation, while fine-sized coal (0.5–50 mm) and slimes (below 0. are then subjected to flotation separation. The crushed coal is classified by particle size using screening equipment, and coal of different particle sizes is sent to the corresponding coal beneficiation equipment. 2. Jigging Separation
Jig Preparation:
Coarse and medium-sized coal is separated using a jig. The jig utilizes pulsating water to stratify coal and impurities based on density. The lighter clean coal rises to the upper layer, while the heavier 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, clean coal and impurities are stratified; the clean coal is collected through an overflow chute or discharge device, while impurities are discharged through a tailings outlet. Flotation Separation
Grinding:
Coarse and fine coal particles need further grinding before entering the flotation machine to achieve a suitable size 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), it is 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. Coking coal processing
Dewatering:
After jigging coal preparation and froth flotation coal preparation, the clean coal contains a certain amount of moisture and 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:
After dewatering, the clean coal is stored and transported. To prevent moisture absorption and spontaneous combustion during storage and transportation, protective measures are required, such as using coal sheds or sealed stockyards for storage. Tailings Management
Tailings Disposal:
The tailings generated during jigging and flotation processes (primarily gangue and impurities) are discharged via discharge devices to a designated tailings management area.
Tailings Dewatering and Wastewater Treatment:
The moisture contained in the tailings is further treated through thickeners or filters for dewatering. The solid tailings are then stockpiled 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
Coking coal is a type of coal used for producing high-quality coke in coking processes, and its quality and properties directly affect the coking process and the quality of the resulting coke. The middlings of coking coal are intermediate products between clean coal and gangue. The ash content of coking Middlingss is relatively high, possibly reaching about 25%–40%. Its caking and coking properties are inferior to those of Coking clean coal. Coking Middlingss are generally not suitable for the production of high-quality coke, as their higher impurity content can negatively affect quality indicators such as coke strength and pore structure. However, in some applications where coke quality requirements are slightly lower, or after special treatment, coking Middlingss can be partially utilized for coke production or used for other industrial combustion purposes, such as a fuel for industrial boilers. However, the impact of harmful components such as sulfur content on the environment and equipment must be considered.
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 flotation combined coal washing is an efficient and flexible coal preparation process that effectively handles coal of different particle sizes and qualities by combining jigging and flotation methods. Its production process includes coal crushing and screening, jigging separation, grinding, flotation separation, clean coal processing, and tailings management. This process 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.