Red mud-based composite binder and preparation and application thereof

Abstract

This invention discloses a red mud-based composite pellet binder and its preparation and application, belonging to the field of pellet preparation technology. The composite binder is based on the mass percentage addition of metallurgical mineral powder, with the following components: 5-15% red mud, 0.8-2.0% main organic binder, and 0.02-0.04% ammonium formate. The main organic binder is one or a combination of industrial pregelatinized starch (gelatinization degree ≥90%) and medium-viscosity CMC (2% aqueous solution viscosity 5000-20000 mPa·s at 25℃, degree of substitution ≥0.6) (starch:CMC=1:0.2-0.5). The red mud is pretreated to a moisture content of 3%-10% (excluding boundary values), a particle size ≤200 mesh (specific surface area ≥300m² / kg), and impurities with a particle size >1mm are removed. This invention first prepares an organic binder slurry, adds pretreated red mud and ammonium formate to form a composite binder slurry, then mixes it with mineral powder in steps with water, pelletizes, and calcines to obtain the finished pellets. Ammonium formate, acting as a trace catalyst, achieves catalytic cross-linking at the organic-inorganic interface, constructing a synergistic system of "organic bonding-inorganic reinforcement-interfacial catalysis," thus overcoming the shortcomings of existing red mud-based binders, such as weak interfacial bonding and poor performance. This invention can completely replace traditional bentonite, achieving a green pellet drop strength ≥4.5 times / 0.5m, a calcination strength of 2850-3280N / pellet, and reducing binder costs by 30-50%. It realizes high-value utilization of red mud resources, is compatible with metallurgical powders such as iron ore, manganese ore, and chromium ore, requires no modification to existing production lines, is easy to industrialize, and possesses significant economic, environmental, and industrial application value.