Production of fuel briquettes from coal waste fines - 1582
- *Abstract
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Overview
Coal fines are an unavoidable by-product of coal mining, and more than twobillion tons of coal waste fines are stored in slurry ponds and gob piles in the U.S., particularlyin Appalachia. These coal waste fines can pose serious risks to human life and health, but unfortunately, the commercial utilization of these wastefines is hindered by their high and difficult to remove moisture content, whichlowers heating/market value and renders them difficult to handle and transport.
Forming the fines into a briquetted fuelcan resolve these issues. However, poorflow properties of wet fines and low green strength of briquettes made from thismaterial requires that the fines be dried prior to briquetting. Historically,fluidized bed dryers have been used to dry wet coal fines, but due to their high fire/explosionpotential, operating permits for fluidized-bed dryers can no longer be obtainedin the U.S. Thus far there has been an absence of an economically-viable method to recoverand utilize this vast resource. To resolve this problem, UK researchers have developed a technology that is suitable for processing low-value, wet coalfines into a flowable, high-value fuel that can be easily transported.
Invention
UK researchers have developed a two-step approach for producing a high-value briquetted fuel from alow-value waste. This starting material may be high-moisture fine coal that is discarded in the waste-stream slurry at a coal preparation plant, or it may be a blend of wet fine coal and biomass.
First, pellets are formed in adrum pelletizer and then dried in amoving bed dryer. The dried coal pellets providea hot, flowable feedstock to the briquetter hopper resulting in fewer runstoppages and a more consistent briquetted product. Delivering the pellets to the briquetter whilehot also reduces the amount of binder that must be added to obtain a targetedstrength. Biomass may alsobe added directly to the briquetter hopper where it is blended in situ andco-briquetted with coal fines. The result is a dry, flowable briquette that canbe stored, processed, and burned in existing equipment used to produceelectricity from coal.
Applications
- production of fuel briquettes
Advantages
- well-suited for processing high-moisture wastecoal fines
- reduces the amount of binder that must be addedfor a given briquette strength
- reduces release of fugitive dust during drying, shipping,and handling
- canprocess and burn the biomass in the existing equipment
- no need for additional capital investment
IP Status: U.S. Patent No. 8,753,410
- 国家/地区
- 美国
