Two-Stage Agglomeration for Non-Caking Coal Briquettes

The coking process is segmented into two distinct stages: a first coking stage at lower temperature (400-700°C) to form green briquettes with initial structural integrity, and a second coking stage at higher temperature (700-1100°C) to achieve final coke quality. This segmentation allows non-conventional feedstocks to be processed progressively, building strength in stages rather than requiring immediate high-temperature resistance

Green briquettes are formed and partially coked before being subjected to final high-temperature coking. The preliminary low-temperature coking stage pre-cooks the feedstock and establishes basic structural framework, so that when the briquettes enter the second coking stage, they already have improved integrity and can withstand the thermal and mechanical stresses of high-temperature processing

The feedstock is pre-treated in a pugmill mixer where water and binders are uniformly distributed throughout the material before briquetting. This preliminary water distribution ensures that moisture is evenly incorporated, allowing the briquettes to maintain flexibility during handling while developing sufficient strength through the controlled coking process

Binders are introduced as intermediary substances that mediate between water and coal particles. The binders absorb water and create binding bridges between particles, allowing the system to maintain both flexibility (through water) and strength (through binder-mediated particle bonding) simultaneously during the briquetting and initial drying phases

The coking operation is divided into two sequential stages with distinct temperature ranges and duration parameters. The first stage (400-700°C, 0.5-2 hours) focuses on moisture removal and initial carbonization, while the second stage (700-1100°C, 1-4 hours) completes the coking process. This segmentation provides reliable briquette integrity by progressively transforming the material rather than subjecting it to abrupt high-temperature stress

The coking process utilizes systematic parameter changes across two stages: temperature increases from 400-700°C to 700-1100°C, and residence time is allocated as 0.5-2 hours in the first stage and 1-4 hours in the second stage. These controlled parameter transitions ensure that non-caking coals undergo gradual structural transformation, maintaining reliability while achieving the necessary coke quality

Binders serve as intermediaries that enable effective particle bonding at lower compression forces. The binders create adhesive bridges between coal particles, allowing the formation of strong green briquettes without requiring excessive mechanical pressure, thereby avoiding the need to add large amounts of water that would complicate subsequent drying and coking operations

The reliance on mechanical compression to achieve particle bonding is partially replaced by chemical bonding mechanisms provided by binders. Instead of depending solely on high mechanical pressure to force particles together, the binders provide chemical adhesion that maintains briquette integrity at lower compression levels, simplifying the moisture management requirements