briquettes



briquettes defined in 1909 year

briquettes - briquettes (block-fuel);
briquettes - Considering the vast quantities of inflammable waste material that exist and are either destroyed or disposed of at nominal prices, it is to be wondered at that the Briquette industry is not in evidence to a greater extent than it now is. Of course waste material of this kind is not always near towns, and in the case of sawdust it is almost confined to remote districts where lumber mills exist. In the case of coal dust, however, this is more readily available, while peat is, in many parts, available in bulk near centres of civilization. Probably peat is the most difficult to deal with, but owing to its availability and unlimited quantity every effort is being made to perfect its conversion into a solid coal-like fuel.

Coal-Dust Briquettes

(a) The ingredients required are coal-dust and any binding material easily procured. Clay can be used for binding a cheap article, but has the fault of caking in a hot fire, and rendering the ash very difficult to remove.

The process in general use is to have steam jacketed pans, and to mix with the coal-dust, a certain proportion of resin, pitch, and crude naphtha, and after these articles have undergone a thorough mixing they are let out through a door at the bottom of the pan, -and passed on to a press. In this, they are pressed into blocks of a suitable size, and, on leaving it, they are ready for the market.

If clay is used as a binding material, it greatly improves the look of the product if it is finished off with a coat of crude resin, by melting the resin and dipping the blocks into it.

There is very little skill required in the production of these goods, when once the proper proportions of the different ingredients are obtained.

Almost any resinous or tarry matter may be used in the manufacture,, Seaweed, boiled down in water, may be advantageously employed when collieries are situated near the coast. The weed on being boiled for some hours produces a glutinous mass, and acts as a good binding material; it should be mixed with the coal dust in the pan. Pine saw-dust, 7½ per cent, mixed with the coal-dust before going into the pan improves the quality of the briquettes. Any kind of sawdust may be used, but pine is the best, owing to its resinous nature. The quantity of each binding material necessary can be best ascertained by experiment and presents no difficulty.

(b) There are two ways of treating coal-dust for briquettes, one with heat and one without. With heat it is necessary to have some kind of boiling pan such as those used for boiling asphalt or for tar paving. The dust is put in this with 18 lb. of coal-tar pitch to each 100 lb. of coal-dust. They are well heated and worked with a paddle so that the two ingredients may blend as perfectly as possible. When the mixture appears to be ready, it is taken out in suitable amounts and filled into moulds. No pressure is required, but the moulds must be well filled. In some cases moulds are dispensed with, the material being patted or beaten into blocks with wooden bats; or, occasionally, the briquette is preferred ball-shaped, about the size of a very large orange.

The cold method requires coal-dust and coal-tar, no pitch being required as this needs heat to make it fluid. The coal-dust may be put into a pan or tank, or it may be made into a heap in the open. A space is then formed in the middle and the tar poured into this. It is then worked with a shovel or paddle to the consistency of stiff mortar, then put direct in to the moulds, or beaten into blocks, or rolled into balls, as just explained. These take longer to become hard than the hot process. An economy can be effected by using part tar and part water for the liquid ingredient. The utmost proportion of water is one part to each two parts of tar. The total quantity of fluid required for the coal-dust must be judged by the mixer, he adding a little at the time like mixing mortar or concrete.

Sawdust Briquettes

Sawdust in cake form appears to have been used as fuel in Germany with rather promising results. United States Consul, A. L. Frankenthal, writing from Berne, Switzerland, says that the sawdust cakes are octagon-shaped, 6½ in. long, 3½ in. wide, and ¾ in. thick, weighing about half a pound each. In the district surrounding the factory where these cakes were made the schools were heated by them, the combustion leaving very little ash and proceeding without a large flame. No binding ingredient is said to be used, the sawdust being simply dried and pressed into the desired briquette shape, and owing thus to the absence of tarry or oily substances there is no smoke in burning. The weight of such a briquette indicates the heavy pressure under which it takes its shape, and the edges look like polished oak; in fact, it is heavier than a piece of hard wood of the same size. The demand created by the popularity of the fuel exceeded the supply of sawdust obtainable in the vicinity of the factory, and carloads were, therefore, procured from Sweden, and other distant manufactories. Sawdust, which previously could be had for the asking, demanded a market price as soon as it became known that a certain factory could make use of it. Even then it was profitable to manufacture the briquettes; but, unfortunately, the factory was destroyed by fire, and operations came to a standstill. Making sawdust briquettes of this kind would, therefore, seem to be worth inquiring into further.

Peat Briquettes

(a) During the past fifty years this industry has been placed on a more intelligent basis, due chiefly to the solution of the problem of a cheap production on a large scale. At the present day machine peat is made which stands transportation and the influences of weather, and in many localities even competes with coal. According to a report by the American Institute of Mining Engineers, the method of making machine peat is entirely automatic, the machinery for cutting the peat, elevating it to the press, and conveying the slabs to the drying ground being mounted on a truck which travels into the bog sometimes under its own steam. This arrangement is made for a capacity of from 50 to 80 tons in 24 hours, and costs from 800l. to 1200l. at the factory. The truck travels on rails, and the bog is gradually exhausted by cutting each new trench next to the one just completed. An excavating elevator drops the raw peat into the machine, where it is disintegrated, kneaded, and forced through a mouthpiece in the form of an endless plastic band, upon a truck on which it is cut, by a series of adjustable knives, into any desired lengths. The pressure required is very slight, and as no water escapes, the chemical composition of the raw material is unchanged. The volume of the peat is reduced about one-half, and the slabs when thoroughly air-dried weigh from 40 lb. to 60 lb. per cub. ft. One man is employed for every 2 or 2½ tons of peat briquettes produced. While the raw peat contains as a rule, between 80 and 90 per cent, of moisture, the air-dried slabs have seldom more than from 15 to 25 per cent. To effect a more thorough drying, large hot-air chambers are used.

The cost of making machine peat in Germany is from 3s. to 4s. per ton at the outset, which allows a considerable depreciation for the machinery. This figure is taken from the Schilt Works, near Oldenburg, and from the Eainbow Works, near Langen, on the Elbe. There is a peat bog at Magdeburg which yields annually about 540l. worth of machine peat per acre, while the cost of manufacture is but 180l., thus leaving a profit of 360l. per acre. The average depth of this bog is 40 ft. The experience gained with the use of press-peat as locomotive fuel in Bavaria, Austria, Sweden, Russia, and Ireland is stated to be very satisfactory. The utilisation of dried press-peat for gas making and as a substitute for coal and charcoal is also stated to be satisfactory. The problem to produce from a poor grade of fuel containing from 70 to 90 per cent, of moisture, a briquette which can compete with coal, or can make up deficiences in the fuel supply, is a very serious one. Huge masses of raw material have to be handled and cleansed from foreign matter, and tons of water have to be expelled in order to obtain a limited quantity of valuable fuel. Many processes have been tried and abandoned, as they proved to be too expensive. A few plants in Germany and Holland are working on similar lines with brown coal, but a large portion of the water is expelled mechanically before drying by heat. Much labour and money have been expended in Germany on the development of the peat industry, and nearly all modern methods have originated in that country. Great efforts are being made to establish the manufacture of solid peat briquettes as a permanent commercial industry. In Holland there are many acres of peat bog excavators under cultivation, and supporting from 300 to 350 people per square mile. In some water-filled bog trenches fisheries are established on a large scale. - 'Journal of the Society of Arts.'

(b) An improved peat briquette is being made at Charlton, Kent. The chief novelty lies in the method of expelling the water from the raw material. The peat, as it comes from the ground, is inserted into a vertical cylinder, perforated at its surface and made to revolve rapidly about its vertical axis. Electricity is used in the expelling process, a current being caused to pass from the axis, through the peat, to the surface of the cylinder, being conducted away by brushes. The effect of the current is to loosen the fibres of the peat, release moisture, and so allow of a more free and perfect escape of water. The water, as will be understood, is thrown off by centrifugal force when the cylinder is rotated. The electric current is considered to have a breaking up effect on the fibres so that the subsequent compression of the treated material produces a solid and fairly hard block.

Of course briquettes, of whatever combustible they may be made, will serve a useful purpose for fuel, so that their practicability is confined to the question of cost. A good peat briquette can produce but half the heat units per pound that good steam coal will, so that 2 lb. of best peat fuel may be required in place of 1 lb. of coal, and, in addition, the peat has a greater bulk for a given weight. It would seem, therefore, that in treating peat for this purpose, the cost must be very carefully considered, and when power for both water expulsion and electrical treatment must be provided, the difference between profit and loss on the product will need very carefully going into.

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