| 摘要 |
Lignite or peat are ground to particle sizes below 50 mesh and then subjected to washing in a detergent solution, where the inert materials and the unbound ash are removed. Following washing, they are treated in an acid bath containing a 15-20 % strong hydrochloric acid solution in a volume ratio of 4-12 times the processed lignite mass. The acid is continuously recycled and fresh make-up acid is added to maintain a constant acid strength. The addition of a known quantity of sulphuric acid ensures that the dissolved ash compounds are converted into sulphates, which, being insoluble in hydrochloric acid, settle and are periodically removed from the tank. Thus demineralisation of the lignite up to an extent of 60-80 % can be achieved with a similar reduction in its moisture and sulphur content. The processed lignite is then centrifuged and up to 80 % of the hydrochloric acid absorbed is recovered. Recovery of the absorbed acid is completed by washing a centrifuge with the use of the minimum quantity of water. Following neutralisation, the washates are processed in a desalination unit, where clean water and molecular chlorine are recovered. Processing of solid fuels, according to this method, achieves the increase of the calorific value of the product stream by 3 to 5 times. |
