Fuel Product and Process

Abstract

A process for producing fuel pellets is described. The pellets are obtainable from a particulate carbon-based material and a binder, the process comprising the following steps: admixing the material and binder, and agglomerating the so-formed mixture by tumbling. The tumbling action, such as in a rotary drum, serves to agglomerate the particles and bind the mixture into the pellets, usually with a variable size distribution. No mechanical compression force is required, and with the binders used, the process can be carried out at ambient temperature. The process provides a simple but efficient process for using waste carbon-based materials, and forming a useable fuel product, which is easily transportable and efficiently combustible. Rotating drum or pan agglomerators are relatively low cost to build, and are capable of very high tonnage throughputs. Customised products can be produced and the process enhances the economics of ash and sulphur removal in coal upgrade plants.

1 . A process for producing rigid fuel pellets from a particulate carbon-based material and a binder, comprising of the following steps: 
 admixing the material and binder, and agglomerating the so-formed mixture by tumbling to form the pellets,    wherein the binder is silicate-based and includes one or more surfactants able to form rigid fuel pellets as the process is carried out at ambient temperature.    
   
   
       2 . A process as claimed in  claim 1  carried out as a single stage process.  
   
   
       3 . A process as claimed in  claim 1  wherein the process is carried out without requiring a separate active curing step or steps.  
   
   
       4 . A process as claimed in  claim 1  wherein the so-formed rigid pellets cure after tumbling at ambient temperature.  
   
   
       5 . A process as claimed in  claim 1  wherein the pellets form a hardened shell.  
   
   
       6 . A process as claimed in  claim 1  adapted to provide pellets of a variable size distribution.  
   
   
       7 . A process as claimed in  claim 1  wherein the particulate material and/or binder mixture includes water.  
   
   
       8 . A process as claimed in  claim 8  wherein the binder includes water prior to admixture with the particulate material.  
   
   
       9 . A process as claimed in  claim 1  wherein the particulate material is generally of a maximum size or grade of about 3 mm or lower.  
   
   
       10 . A process as claimed in  claim 1  wherein the particulate material is coal dust or coal fines.  
   
   
       11 . A process as claimed in  claim 1  wherein the particulate material is partly, substantially or wholly peat.  
   
   
       12 . A process as claimed in  claim 11  wherein the peat is in combination with coal fines.  
   
   
       13 . A process as claimed in  claim 1  wherein the particulate material is a combination of two or more starting materials.  
   
   
       14 . A process as claimed in  claim 1  wherein the binder is partly, wholly or substantially sodium silicate or potassium silicate.  
   
   
       15 . A process as claimed in  claim 1  wherein the process includes the addition of one or more further ingredients.  
   
   
       16 . A process as claimed in  claim 15  wherein the or each further ingredient is selected from the group comprising: lime, inorganic binders, cements and waterproofing additives.  
   
   
       17 . A process as claimed in  claim 1  wherein the particulate material and binder are at least partly mixed with agitation.  
   
   
       18 . A process as claimed in  claim 1  wherein the binder is sprayed on to the particulate material.  
   
   
       19 . A process as claimed in  claim 1  wherein the particulate material is moving prior to and/or during mixture with the binder.  
   
   
       20 . A process as claimed in  claim 1  wherein the pellets have a spherical or ovoid shape.  
   
   
       21 . A process as claimed in  claim 1  wherein the pellets are screened after tumbling.  
   
   
       22 . A process as claimed in  claim 1  wherein the tumbling is carried out in a rotary drum.  
   
   
       23 . A process as claimed in  claim 1  wherein the process does not require any pre-treatment of the particulate carbon-based material.  
   
   
       24 . A process as claimed in  claim 1  for reducing moisture in the carbon-based material, preferably to less than 5%, compared with the weight of the moisture in particulate carbon-based starting material.  
   
   
       25 . A process as claimed in  claim 1  wherein the mixing of the particulate material and binder occurs by the tumbling.  
   
   
       26 . A process as claimed in  claim 1  further comprising the step of grinding the formed pellets.  
   
   
       27 . A rigid fuel pellet product formable at ambient temperature by agglomeration of a particulate carbon-based material and a silicate-based binder including one or more surfactants.  
   
   
       28 . A fuel pellet product formed by a process of  claim 1 .  
   
   
       29 . A fuel pellet product as claimed in  claim 27  ready for combustion.  
   
   
       30 . A fuel pellet as claimed in  claim 27  wherein the pellet product includes one or more sulphur-absorbing agents.  
   
   
       31 . A fuel pellet as claimed in  claim 27  in a ground form, preferably ready for fuel-burning.  
   
   
       32 . A fuel pellet as claimed in  claim 27  having a hardened shell.  
   
   
       33 . A fuel pellet as claimed in  claim 27  having a variable density towards its core.  
   
   
       34 . A fuel pellet as claimed in  claim 27  having a dry interior.  
   
   
       35 . A fuel pellet as claimed in  claim 27  having sufficient rigidity after tumbling to allow handling, stacking and/or transportation without any significant breakage.  
   
   
       36 . A fuel pellet as claimed in  claim 27  being wholly or substantially combustible, so as to leave little or no combustible fuel in the ash.  
   
   
       37 . A fuel pellet as claimed in  claim 27  being formed from a coal dust or coal fines.  
   
   
       38 . A fuel pellet as claimed in  claim 27  having substantially no sulphur emission during combustion, preferably 70-90% or more reduction in sulphur emission.  
   
   
       39 . A fuel pellet as claimed in  claim 27  wherein the moisture in the pellet is substantially less than the moisture in the starting particulate material.  
   
   
       40 . A fuel pellet as claimed in  claim 27  wherein the pellet has a moisture content of <5%.