Peat and its Uses as Fertilizer and Fuel Part 12

With moderate activity, the five men will lift and lay out 12,000 sods (3000 cubic feet,) daily, and it is not uncommon that five first-rate hands get out 16,800 peats (4200 cubic feet,) in this time.

A gang of five men, working as described, suffices for cutting out a bed of four feet of solid peat. When the excavation is to be made deeper, a sixth man, the "Hanker," is needful for economical work; and with his help the cutting may be extended down to nine and a half feet; i. e.

through eight feet of solid peat. The cutting is carried down at first, four feet as before, but the peats are carried 50 feet further, in order to leave room for those to be subsequently lifted. The "Hanker" aids here, with a second wheel-barrow. In taking out the lower peat, the "Hanker" stands on the bottom of the first excavation, receives the blocks from the Diggers, on a broad wooden shovel, and hands them up to the Loader; while the Wheeler, having only the usual distance to carry them, lays them out in the drying rows without difficulty.

After a little drying in the rows, the peats are gradually built up into narrow piles, like a brick wall of one and a half bricks thickness.

These piles are usually raised by women. They are made in the s.p.a.ces between the rows, and are laid up one course at a time, so that each block may dry considerably, before it is covered by another. A woman can lay up 12,000 peats daily--the number lifted by 5 men--and as it requires about a month of good weather to give each course time (two days) to dry, she is able to pile for 30 gangs of workmen. If the weather be very favorable, the peats may be stacked or put into sheds, in a few days after the piling is finished. Stacking is usually practised. The stacks are carefully laid up in cylindrical form, and contain 200 to 500 cubic feet. When the stacks are properly built, the peat suffers but little from the weather.

According to Schroeder, from whose account (Dingler's Polytechnisches Journal, Bd. 156, S. 128) the above statements are derived, the peats excavated under his direction, in drying thoroughly, shrank to about one-fourth of their original bulk (became 12 inches x 3 inches x 3 inches,) and to one-seventh or one-eighth of their original weight.

c. _Machines for Cutting Peat._

In North Prussia, the Peat Cutting Machine of Brosowsky, see fig. 4, is extensively employed. It consists of a cutter, made like the four sides of a box, but with oblique edges, _a_, which by its own weight, and by means of a crank and rack-work, operated by men, is forced down into the peat to a depth that may reach 20 feet. It can cut only at the edge of a ditch or excavation, and when it has penetrated sufficiently, a spade like blade, _d_, is driven under the cutter by means of levers _c_, and thus a ma.s.s is loosened, having a vertical length of 10 feet or more, and whose other dimensions are about 24 28 inches. This is lifted by reversing the crank motion, and is then cut up by the spade into blocks of 14 inches 6 inches 5 inches. Each parallelopipedon of peat, cut to a depth of 10 feet, makes 144 sods, and this number can be cut in less than 10 minutes. Four hands will cut and lay out to dry, 12,000 to 14,000 peats daily, or 3100 cubic feet. One great advantage of this machine consists in the circ.u.mstance that it can be used to raise peat from below the surface of water, rendering drainage in many cases unnecessary. Independently of this, it appears to be highly labor saving, since 1300 machines were put to use in Mecklenburg and Pomerania in about 5 years from its introduction. The Mecklenburg moors are now traversed by ca.n.a.ls, cut by this machine, which are used for the transportation of the peat to market.[18]

[Ill.u.s.tration: Fig. 4.--BROSOWSKY'S PEAT CUTTER.]

Lepreux in Paris, has invented a similar but more complicated machine, which is said to be very effective in its operation. According to Herve Mangon, this machine, when worked by two men, raises and cuts 40,000 peats daily, of which seven make one cubic foot, equal to 5600 cubic feet. The saving in expense by using this machine[19] is said to be 70 _per cent._, when the peat to be raised is under water.

11.--_The Dredging of Peat._

When peat exists, not as a coherent more or less fibrous ma.s.s, but as a paste or mud, saturated with water, it cannot be raised and formed by the methods above described.

In such cases the peat is dredged from the bottom of the bog by means of an iron scoop, like a pail with sharp upper edges, which is fastened to a long handle. The bottom is made of coa.r.s.e sacking, so that the water may run off. Sometimes, a stout ring of iron with a bag attached, is employed in the same way. The fine peat is emptied from the dredge upon the ground, where it remains, until the water has been absorbed or has evaporated, so far as to leave the ma.s.s somewhat firm and plastic. In the mean time, a drying bed is prepared by smoothing, and, if needful, stamping a sufficient s.p.a.ce of ground, and enclosing it in boards 14 inches wide, set on edge. Into this bed the partially dried peat is thrown, and, as it cracks on the surface by drying, it is compressed by blows with a heavy mallet or flail, or by treading it with flat boards, attached to the feet, somewhat like snow shoes. By this treatment the ma.s.s is reduced to a continuous sheet of less than one-half its first thickness, and becomes so firm, that a man's step gives little impression in it. The boards are now removed, and it is cut into blocks by means of a very thin, sharp spade. Every other block being lifted out and placed crosswise upon those remaining, air is admitted to the whole and the drying goes on rapidly. This kind of peat is usually of excellent quality. In North Germany it is called "Baggertorf," i. e.

mud-peat.

Peat is sometimes dredged by machinery, as will be noticed hereafter.

12.--_The Moulding of Peat._

When black, earthy or pitchy peat cannot be cut, and is not so saturated with water as to make a mud; it is, after raking or picking out roots, etc., often worked into a paste by the hands or feet, with addition of water, until it can be formed into blocks which, by slow drying, acquire great firmness. In Ireland this product is termed "hand-peat." In Germany it is called "Formtorf," _i. e._ moulded peat, or "Backtorf,"

_i. e._ baked peat.

The shaping is sometimes accomplished by plastering the soft ma.s.s into wooden moulds, as in making bricks.

13.--_Preparation of Peat Fuel by Machinery, etc._

Within the last 15 years, numerous inventions have been made with a view to improving the quality of peat fuel, as well as to expedite its production. These inventions are directed to the following points, viz.: 1. _Condensation_ of the peat, so as bring more fuel into a given s.p.a.ce, thus making it capable of giving out an intenser heat; at the same time increasing its hardness and toughness, and rendering it easier and more economical of transportation. 2. _Drying_ by artificial heat or reducing the amount of water from 20 or 25 _per cent._ to half that quant.i.ty or less. This exalts the heating power in no inconsiderable degree. 3.

_Charring._ Peat-charcoal is as much better than peat, for use where intense heat is required, as wood charcoal is better than wood. 4.

_Purifying from useless matters._ Separation of earthy admixtures which are incombustible and hinder draught.

A.--_Condensation by Pressure._

_Pressing Wet Peat._--The condensation of peat was first attempted by subjecting the fresh, wet material, to severe pressure. As long ago as the year 1821, Pernitzsch, in Saxony, prepared peat by this method, and shortly afterwards Lord Willoughby d'Eresby, in Scotland, and others, adopted the same principle. Simple pressure will, indeed, bring fresh peat at once into much smaller bulk; but, if the peat be fibrous and light, and for this reason require condensation, it is also elastic, and, when the pressure is relieved, it acquires again much of its original volume.

Furthermore, although pressure will squeeze out much water from a saturated well-ripened peat, the complete drying of the pressed blocks usually requires as much or more time than that of the unpressed material, on account of the closeness of texture of the surface produced by the pressure.

The advantages of subjecting fresh peat to pressure in the ordinary presses, it is found, are more than offset by the expense of the operation, and it is therefore unnecessary to give the subject further attention.

Fresh peat appears however to have been advantageously pressed by other mechanical means. Two methods require notice.

_Mannhardt's Method_, invented about the year 1858, has been practically applied on the large scale at _Schleissheim_, Bavaria. Mannhardt's machine consists of two colossal iron rolls, each of 15 feet diameter, and 6-1/2 feet length, geared into each other so as to revolve horizontally in opposite directions and with equal velocity. These rolls are hollow, their circ.u.mference consists of stout iron plate perforated with numerous small holes, and is supported by iron bars which connect the ends of the roll, having intervals between them of about one inch.

Each roll is covered by an endless band of hair cloth, stretched over and kept in place by rollers. The rolls are operated by a steam engine of 12 horse power. The fresh peat is thrown into a hopper, and pa.s.sing between the rolls, loses a considerable share of its water, issuing as a broad continuous sheet, which is divided into blocks by an arrangement presently to be described. The cloth, covering the rolls, must have great strength, sufficient porosity to allow water to pa.s.s it freely, and such closeness of texture as to retain the fine particles of peat.

Many trials have led to the use of a fabric, specially made for the purpose, of goat's hair. The cloth for each pair of rolls, costs $160.

The peat at Schleissheim is about 5 feet in depth, and consists of a dark-brown mud or paste, free from stones and sticks, and penetrated only by fine fibers. The peat is thrown up on the edge of a ditch, and after draining, is moved on a tram-way to the machine. It is there thrown upon a chain of buckets, which deliver it at the hopper above the rolls. The rolls revolve once in 7-1/3 minutes and at each revolution turn out a sheet of peat, which cuts into 528 blocks. Each block has, when moist, a length of about 12 inches, by 5 inches of width and 1-1/4 inches of thickness, and weighs on the average 1-1/2 lbs. The water that is pressed out of the peat, falls within the rolls and is conducted away; it is but slightly turbid from suspended particles. The band of pressed peat is divided in one direction as it is formed, by narrow slats which are secured horizontally to the press-cloth, at about 5 inches distance from each other. The further division of the peat is accomplished by a series of six circular saws, under which the peat is carried as it is released from the rolls, by a system of endless cords strung over rollers. These cords run parallel until the peat pa.s.ses the saws; thenceforth they radiate, so that the peat-blocks are separated somewhat from each other. They are carried on until they reach a roll, over which they are delivered upon drying lattices. The latter move regularly under the roll; the peats arrange themselves upon them edgewise, one leaning against the other, so as to admit of free circulation of air. The lattices are loaded upon cars, and moved on a tram-way to the drying ground, where they are set up in frames.

The peat-cake separates well from the press-cloths; but the pores of the latter become somewhat choked by fine particles that penetrate them.

They are therefore washed at each revolution by pa.s.sing before a pipe from which issue, against them, a number of jets of water under high pressure. The blocks, after leaving the machine, are soft, and require 5 or 6 days to become air-dry. When dry they are dense and of good quality, but not better than the same raw material yields by simple moulding. The capacity of the rolls, which easily turn out 100,000 peats in 24 hours, greatly exceeds at present that of the drying arrangements, and for this reason the works are not, as yet, remunerative. The rolls are, in reality, a simple forming machine. The pressure they exert on the peat, is but inconsiderable, owing to its soft pasty character; and since the pair of rolls costs $8000 and can only be worked 3 to 4 months, this method must be regarded rather as an ingenious and instructive essay in the art of making peat-fuel, than as a practical success. The persevering efforts of the inventor may yet overcome all difficulties and prove the complete efficacy of the method. It is especially important, that blocks of greater thickness should be produced, since those now made, pack together too closely in the fire.

_Neustadt Method._--At Neustadt, in Hanover, a loose-textured fibrous peat was prepared for metallurgical use in 1860, by pa.s.sing through iron rolls of ordinary construction. The peat was thereby reduced two-thirds in bulk, burned more regularly, gave a coherent coal, and withstood carriage better. The peat was, however, first cut into sods of regular size, and these were fed into the rollers by boys.

b. _Pressing Air-dried Peat._

Some kinds of peat, when in the air-dry and pulverized state, yield by great pressure very firm, excellent, and economical fuel.

_Lithuanian Process._--In Lithuania, according to Leo,[20] the following method is extensively adopted. The bog is drained, the surface moss or gra.s.s-turf and roots are removed, and then the peat is broken up by a simple spade-plow, in furrows 2 inches wide and 8 or 10 inches deep. The broken peat is repeatedly traversed with wooden harrows, and is thus pulverized and dried. When suitably dry, it is carried to a magazine, where it is rammed into moulds by a simple stamp of two hundred pounds weight. The broken peat is reduced to two-fifths its first bulk, and the blocks thus formed are so hard, as to admit of cutting with a saw or ax without fracture. They require no further drying, are of a deep-brown color, with l.u.s.trous surfaces, and their preparation may go on in winter with the stock of broken peat, which is acc.u.mulated in the favorable weather of summer. In this manufacture there is no waste of material.

The peat is dry enough for pressing when, after forming in the hands to a ball, it will not firmly retain this shape, but on being let fall to the ground, breaks to powder. The entire cost of preparing 1000 peats for use, or market, was 2 Thalers, or $1.40. Thirty peats, or "stones"

as they are called from their hardness, have the bulk of two cubic feet, and weigh 160 lbs. The cost of preparing a hundred weight, was therefore, (in 1859,) four Silver-groschen, or about 10 cents.

The stamp is of simple construction, somewhat like a pile driver, the mould and face of the ram being made of cast iron. The above process is not applicable to _fibrous peat_.

c. _Pressing Hot-dried Peat._

The two methods to be next described, are similar to the last mentioned, save that the peat is _hot-pressed_.

_Gwynne's Method._--In 1853, Gwynne of London, patented machinery and a method for condensing peat for fuel. His process consisted, first, in rapidly drying and pulverizing the fresh peat by a centrifugal machine, or by pa.s.sing between rollers, and subsequent exposure to heat in revolving cylinders; and, second, in compressing the dry peat-powder in a powerful press at a high temperature, about 180 F. By this heat it is claimed, that the peat is not only thoroughly dried, but is likewise partially decomposed; _bituminous matters being developed, which cement the particles to a hard dense ma.s.s_. Gwynne's machinery was expensive and complicated, and although an excellent fuel was produced, the process appears not to have been carried put on the large scale with pecuniary success.

A specimen of so-called "Peat coal" in the author's possession, made in Ma.s.sachusetts some years ago, under Gwynne's patent, appears to consist of pulverized peat, prepared as above described; but contains an admixture of rosin. It must have been an excellent fuel, but could not at that time compete with coal in this country.

_Exter's Method._[21]

[Ill.u.s.tration: Fig. 5.--EXTER'S DRYING OVEN.]

[Ill.u.s.tration: Fig. 6.--EXTER'S DRYING OVEN.]

In 1856, Exter, of Bavaria, carried into operation on an extensive scale, a plan of preparing peat-fuel in some respects not unlike the last mentioned method. Exter's works, belonging to the Bavarian Government, are on the Haspelmoor, situated between Augsburg and Munich.

According to Ruehlmann, who examined them at the command of the Hanoverian Government in 1857, the method is as follows:--1. The bog is laid dry by drains and the surface is cleared of bushes, roots, and gra.s.s-turf, down to good peat. 2. The peat is broken up superficially to the depth of about one inch, by a gang of three plows, propelled by a portable steam engine. 3. The peat is further pulverized by a harrow, drawn by a yoke of oxen. 4. In two or three days after harrowing, the peat is turned by an implement like our cultivator, this process being repeated at suitable intervals. 5. The fine and air-dry peat is gathered together by sc.r.a.pers, and loaded into wagons; then drawn by rope connected with the engine, to the press or magazine. 6. If needful, the peat, thus collected, is further pulverized by pa.s.sing it through toothed rollers. 7. The fine peat is now introduced into a complicated drying oven, see figures 5 and 6. It falls through the opening _T_, and is moved by means of the spirals along the horizontal floors _O_, _O_, falling from one to another until it emerges at _Q_. The floors, _O_, _O_, are made by wide and thin iron chambers, through which pa.s.ses waste steam from an engine. The oven is heated further by hot air, which circulates through the ca.n.a.ls _K_, _K_. The peat occupies about one hour in its pa.s.sage through the oven and falls from _Q_, into the press, having a temperature of from 120 to 140Fahrenheit. The press employed at Staltach is essentially the same as that now used at the Kolbermoor, and figured on p. 125. It is a powerful eccentric of simple construction, and turns out continuously 40 finished peats per minute.

These occupy about one-fourth the s.p.a.ce of the peat before pressing, the cubic foot weighing about 72 lbs. The peats are 7 inches long, 3 inches wide, and one half to three quarters of an inch thick, each weighing three quarters of a pound. Three presses furnish annually 180,000 cwt.

of condensed peat, which is used exclusively for firing locomotives. Its specific gravity is 1.14, and its quality as fuel is excellent.

Ruehlmann estimated its cost, at Haspelmoor in 1857, at 8-1/2 Kreuzers, or a little more than 6 cents per cwt., and calculated that by adopting certain obvious improvements, and subst.i.tuting steam power for the labor of men and cattle, the cost might be reduced to 6-1/2 Kreuzers, or a little more than 4 cents per cwt.

Exter's method has been adopted with some modifications at Kolbermoor, near Munich, in Bavaria, at Miskolz, in Hungary, and also at the Neustadt Smelting Works, in Hanover. At the latter place, however, it appears to have been abandoned for the reasons that it could be applied only to the better kinds of peat; and the expense was there so great, that the finished article could not compete with other fuel in the Hanoverian markets.

Details of the mechanical arrangements at present employed on the Kolbermoor, are as follows: After the bog is drained, and the surface cleared of dwarf pines, etc., and suitably leveled, the peat is plowed by steam. This is accomplished in a way which the annexed cut serves to ill.u.s.trate. The plot to be plowed, is traversed through the middle by the railway _x_, _y_. A locomotive _a_, sets in motion an endless wire-rope, which moves upon large horizontal pulleys _o_, _o_, stationed at either border of the land. Four gang plows _b_, _b_, are attached to the rope, and as the latter is set in motion, they break up the strip of peat they pa.s.s over, completely. The locomotive and the pulleys are then moved back, and the process is repeated until the whole field has been plowed. The plows are square frames, carrying six to eight shares and as many coulters.

[Ill.u.s.tration: Fig. 7.]

The press employed at Kolbermoor, is shown in figs. 8 and 9. The hot peat falls into the hopper, _b_, _c_. The plunger _d_, worked in the cavity _e_, by an eccentric, allows the latter to fill with peat as it is withdrawn, and by its advance compresses it into a block. The blocks _m_, once formed, by their friction in the channel _e_, oppose enough resistance to the peat to effect its compression. In order to regulate this resistance according to the varying quality of the peat, the piece of metal _g_, which hangs on a pivot at _o_, is depressed or raised, by the screw _i_, so as to contract or enlarge the channel. At each stroke of the plunger a block is formed, and when the channel _e_ is once filled, the peats fall continuously from its extremity. Their dimensions are 7 inches long, 3-1/2 wide, and 1-1/2 thick.