Fuel and related compositions – Liquid fuels – Aluminum or heavy metal – other than lead – containing
Patent
1987-12-31
1989-09-26
Caldarola, Glenn
Fuel and related compositions
Liquid fuels
Aluminum or heavy metal, other than lead, containing
208426, 44 16R, 44 24, 210728, C10L 516
Patent
active
048697273
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to improvements in the production of coal agglomerates which are suited to long-term storage and/or transportation in the agglomerate form.
BACKGROUND OF THE INVENTION
The formation of coal agglomerates from aqueous slurries containing particulate coal and oil has been widely practiced for many years. Many agglomeration processes have been proposed requiring varying degrees of energy input and oil consumption. Most processes having acceptable energy input requirements and residence times produce relatively oily or sticky coal agglomerates which, while being suitable as a feed stock for the immediate production of a coal-oil mixture, have been found to be unsuitable for long-term storage or transportation due to their stickiness and/or poor physical strength.
Examples of prior art agglomeration processes may be found in U.S. Pat. Nos. 4355999 Masologites, 4302211 Verschun and Australian Patent 534563 (AU-B 54496/80) Dudt. In each of the above processes, long residence times and/or multiple agglomeration stages are required to achieve an acceptable coal agglomerate and even then such products are not necessarily suited to transportation in large bulk carriers of the type which would make transportation of such agglomerates economically viable. In the case of AU-B 54496/80, it will be noted that a four stage process of increasing energy input is required to produce an acceptable agglomerate. Although the agglomerates produced by this process would be acceptably dry (that is, not sticky), the agglomerates would be unlikely to be of sufficient quality to survive transportation without unacceptable production of fines during the transportation process.
It is also well known to reduce the oiliness or stickiness of particulate coal agglomerates by the evaporative de-oiling of such agglomerates. However, such processes have the obvious disadvantage of increasing the energy requirements of the production process since super heated steam must usually be produced to provide the necessary energy to cause evaporation of the oil coating the agglomerates.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved coal agglomeration method which results in the production of better quality agglomerates in shorter residence times.
The invention therefore provides a process for the production of coal agglomerates comprising agitating an aqueous slurry of coal particles in a first agitating means in the presence of a predetermined quantity of oil to form coal agglomerates, further agitating said agglomerates in the presence of further coal particle bearing slurry to improve the dryness and quality of the agglomerates, characterised by the step of transporting the slurry containing said agglomerates in a pipeline to further improve the strength properties of the agglomerates.
The agglomerates produced have been found to be well suited for long-term storage and/or transportation in bulk.
In a preferred form of the invention, the step of transporting the slurry containing the agglomerates in a pipeline follows each of the agitation stages and the transporting is preferably achieved in a pipeline loop.
The consolidation which occurs during formation and circulation of the agglomerate bearing slurry through the pipeline in combination with the two-step coal addition operation permits the production of storage agglomerates having a relatively dry surface. Agglomerates produced in this way show little tendency for sticking together or for attrition during handling operations. For these reasons, they are eminently suited for long-term storage and/or for transportation in bulk. The results achieved were not predictable and the inventors found the improvement in agglomerate quality by the circulation of the slurry in a pipeline quite surprising. The inventors are not yet aware of the physical reasons for the unexpected improvements achieved by the pipeline circulation, but it is clear that the further contact between the agglomerates and the coal particle
REFERENCES:
patent: 4126426 (1978-11-01), Verschuur
patent: 4248697 (1981-02-01), Halvorsen
patent: 4277252 (1981-07-01), Dudt
patent: 4302211 (1981-11-01), Verschuur
patent: 4311488 (1982-01-01), Verschuur
patent: 4355999 (1982-10-01), Masologites
patent: 4455148 (1984-06-01), Nagata et al.
patent: 4492638 (1985-01-01), Hiratsuka et al.
Caldarola Glenn
The Broken Hill Proprietary Company Limited
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