NOVELTY - A pellet binder comprises (wt.%): silicate (60-97), catalyst (3-40), water (balance). The catalyst comprises (wt.%) glycol (10-40), sulfonate (10-20), sulfate (5-10) and water (balance).    USE - For producing pellets at ambient temperature from particulate material (selected from coal dust or coal fines); for forming rigid fuel pellets from a particulate carbon-based material or biomass material (selected from wastewater sludge, sewerage sludge, chicken litter, bonemeal, spent mushroom compost, wood, plant residues including rape seed, hemp seed, corn and sugar cane residues); for producing metal ore pellets from a particulate carbon-based material and a metal ore material (preferably iron ore) (all claimed).    ADVANTAGE - The obtained pellet has a variable density towards its core; is formed from a coal dust or coal fines. The obtained fuel pellet has a moisture content of less than 5% and is not affected by high ash content or sulfur content in the particulate material. The obtained fuel pellet product is a material which is easily storable; easily transportable due to its variable diameter distribution. This enhances stacking concentration, which also reduces abrasion and consequential breakage of the pellets. The obtained fuel pellet product is ready for use as a fuel in many situations, e.g. domestically such as in a home fire or industrially, such as in a power plant; allows a very high percentage of combustion (possibly 100% combustion), so as to leave little or no combustable fuel in the ash; is cost effective. The pellet binder provides less than 3 mm coal/lignite fines which can be pelletized dry or direct from a filtration plant; tonnage throughput which can be 10 tones per hour (community size) up to 300 or 500 tonnes per hour per pelletizing line; high level of automation which is used during pelletizing for accurate control and reagent usage; pellets just air dry while chemically curing; pellets which is handled by bulk handling equipment when cured or alternatively bagged when green; pellet size which is customized from 5-150 mm if required depending upon coal characteristics and process parameters; special heavy duty reagents that can be added for high strength, for rapid cure, for high temperature strength, and for enhanced water resistance; pyrite removal which is reduced or eliminated due to various binder combinations to eliminate SO2 due to gas transfer to form CaSO4 inside the pellet. Due to excellent combustion characteristics, high ash coal fines will ignite and burn with high efficiency. The pellet binder has long lasting combustion, with high percentage carbon combustion; provides less than 20 mm coal which is can be crushed and pelletized with fines for high value pellets; contaminated coal or waste products such as sawdust, rice husks, sewage, animal wastes, petroleum coke or waste oil which is included into the pellets; residual ash that has negligible un-burnt fuel (e.g. coal) residue and is excellent for other industrial uses; lignite and peat which is treated with identical technology or which is blended with other fuel sources to create hybrid pellet fuels with predesigned characteristics such as smokeless burning. The residual ash is also pelletized with similar binder reagents for concrete feedstock, aggregate blending and high porosity landfill.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a single-stage process (M1) for producing pellets at ambient temperature from at least a particulate material and the pellet binder involving: mixing the particulate material and binder; agglomerating the so-formed mixture by tumbling; and curing the pellets after tumbling at ambient temperature to form rigid pellets having a hardened shell;    (2) producing (M2) rigid fuel pellets at ambient temperature from a biomass material and the pellet binder involving: a) mixing the biomass material and binder, and b) agglomerating the so-formed mixture by tumbling at ambient temperature to form pellets; and c) curing the pellets at ambient temperature to form rigid pellets having a hardened shell; and    (3) a pellet whenever formed by the method (M1) and (M2).