Pelletizing Binder Powder Pelletizing

There are three major schools of thought in powder pelletizing, each with its own advantages and disadvantages, different application scenarios, and varying investment and operational costs. No method is flawless; each has its own strengths and weaknesses and is suited to specific application areas. Each pelletizing method has different strength levels, temperature-resistant drum coefficients, and wear coefficients, as well as varying investment and operational costs.      All powder pelletizing processes require uniform mixing in the initial stage. Some require moderate moisture, with different processes having different moisture requirements. Some have no requirements for particle size range, accepting anything from 600 mesh to 10 mesh, while others require raw material particle sizes to fall within a very narrow range. Some can mix carbon, while others cannot. Some raw materials require secondary crushing, while others do not. Some need drying, while others can air-dry naturally. Some not only require drying but also high-temperature calcination.      Therefore, the costs and conditions for heat sources vary, as do the costs of using or not using binders. Calcination and non-calcination also affect the mixing capacity of raw materials.
Briquetting pelletizing      uses high pressure and molds to form pellets or blocks in one step under high pressure, similar to the production processes of powder metallurgy or refractory bricks. The pellets or blocks are then air-dried or oven-dried. The formed bricks can be crushed into blocks, but the drawback is that crushing generates new powder, which must be recycled for re-pelletizing or briquetting, resulting in significant heat loss. The advantage of direct briquetting is its low cost, as it allows for carbon mixing or the combination of various solid wastes, including dust pelletizing, air-drying, and direct smelting. Typically, briquetting can also involve adding small amounts of binders, though some processes do not require binders, depending on the characteristics of the raw materials.
There are many types of binders, and different binders are chosen based on the raw materials and strength requirements. Of course, new binder technologies are continually being explored, often involving mixed binders, such as organic binders that ensure low-temperature strength and high-temperature binders that ensure high-temperature performance.      Most binder-based pelletizing methods do not achieve high strength, with actual strength typically ranging from 100 to 600 Newtons. Temperature resistance is also not very high, usually between 300-800 degrees Celsius, though a few can withstand 1000-1200 degrees Celsius, but at increased cost. Another issue with binders is that they should not contaminate the raw materials or significantly increase smelting power consumption. Binders can also be used for carbon-mixed pelletizing, which is similar to briquetting but does not require high pressure. Typically, the weight ratio of binder usage is between 3-7%, though this varies depending on the process and raw materials.