Millions from Waste by Frederick Arthur Ambrose Talbot - HTML preview

CHAPTER XV
 THE LIFTING-MAGNET AS A WASTE DEVELOPING FORCE

Waste is precarious to handle. The very nature of the material demands that it shall be worked up in the most economical manner. Under the fickle influences normally prevailing upon the market, the margin between profit and loss may suffer such attenuation from inefficient exploitation as to submerge the factor of profit, thus endangering the very practice of utilizing the residue. It is immaterial whether time or labour be the adverse circumstance. The one influence can be quite as ruinous as the other. Should the cumulative effect of the two forces be experienced simultaneously, then the results are almost certain to be devastating and prompt in their action. Consequently, to secure the uttermost benefits attainable it is imperative that the most economical and efficient methods should be employed.

This is particularly the case in the iron and steel trades. The competition between the various nations in this manufacturing field is excitingly keen. It must not be forgotten that, in this industry, waste plays a very prominent part as a raw material. It may be tins rescued from the domestic dust-bin, turnings from the lathe, a worn-out locomotive boiler, or the battered hulk of a steamship snatched from the jaws of the hungry seas through the ingenuity of the salvage engineer.

In the handling of scrap and junk the designing engineer has been strikingly ingenious, resourceful, and free with his expressions of resource. The cranes and other mechanical handling devices, which he has evolved, compel attention for the simple reason that they have been introduced to secure a reduction in the cost of moving the material. In this direction finality is impossible of attainment; the necessity to reduce the cost factor is so urgent and continuous. Creative effort, thus fostered, has achieved a distinct triumph during the past few years. It has evolved a new system of dealing with iron and steel, especially the waste, which is rapidly displacing all other methods which hitherto have held undisputed sway. I refer to the lifting-magnet.

It was a British mind which first conceived the idea of harnessing the magnet to the wheels of the iron industry. Sir William Sturgeon saw no reason why the toy of our childhood days, the pin-attracting properties of which extended us infinite delight and provoked indescribable wonder, should not be devoted to the movement of ponderous masses of steel. So he made the experiment. But his noteworthy effort proved only partially successful. It did not fulfil expectations, not because the designer was wrong in his deductions, but because he conducted the evolution along fallacious lines. But his failure set men thinking. They followed up his reasonings and discovered why he did not record success. The British pioneer had been content to accept the magnet’s familiar form and to reproduce it upon a larger scale to fulfil his objective. This was why he failed. For such as application as he had in his mind’s eye a modification in design was imperative. The German and American experimentors, who followed in his footsteps, quickly realized this circumstance and accordingly abandoned the traditional horse-shoe form for a magnet of flat drum-like shape.

In this modernized and materially changed form the lifting-magnet met with instant success. The Germans were the first to recognize its possibilities, and accordingly developed and popularized its utilization in accordance with their characteristic organized methods, with the result that it was not long before all the leading iron- and steel-works of the country were equipped therewith to their distinct commercial advantage.

So far as America and Britain, the home of the lifting-magnet, have been concerned, progress has been slow and uneventful. The Germans set out to reap advantage from our manufacturing apathy, and to a certain degree succeeded. It remained for the war, with its drain upon cheap labour on the one hand and the necessity to speed up and to increase output on the other, which compelled us to regard the lifting-magnet with enhanced favour. This tendency was accentuated by the urgent requests circulated far and wide to save all waste metal and to turn it over to the country for the production of munitions. In this manner vast quantities of waste metal of every conceivable description were released, which, in turn, led to a demand for handling appliances. Under the conditions which obtained it was imperative that this potential raw material should be handled with the utmost economy, both of time and labour, but native ingenuity had nothing at its command to compare with the lifting-magnet in this connection. Those firms which had been sufficiently enterprising to equip themselves with the German appliance found themselves in an overwhelming superior position, while their lifting-magnets paid for themselves over and over again in the course of a single year.

The national deficiency in supply and its far-reaching adverse effects were remedied through the combined enterprise and initiative of a young electrical engineer and a British manufacturer. The former had followed the German developments very closely and had discovered that, notwithstanding their extravagant claims, these appliances really fell somewhat short of the mark in point of efficiency and economy in operation. Fortified with this knowledge he had promptly designed an appliance of this character, in which the obvious Teuton defects were eliminated, thereby giving a lifting-magnet which represented a decided advance upon the best which Germany could offer.

The Pickett-West lifting-magnet, so named after its designer and manufacturer respectively, is one fully complying with traditional British standards of production, while it also possesses many novel features which have already emphasized their value. It is built along robust lines, so that it completely fulfils the conditions peculiar to its field of application. Moreover, its design can be modified within wide limits to meet the individual requirements of the service for which it is intended, one distinctly ingenious feature being the model fitted with moving fingers, each of which constitutes a magnet in itself, and wherewith the magnet is able to exercise the maximum magnetic gripping power upon the article for the movement of which it is being used.

Without entering into a technical description of this apparatus it may be said to comprise, in its simplest form, an inverted dish with a central pole-piece. Round this pole-piece is built a coil composed of alternate layers of copper of substantial dimensions and insulating material. The coil is enclosed within the inverted dish and a face-plate is bolted in position. Thus the coil which occupies the whole of the case, with a special insulating compound run in under pressure to occupy all the vacant space such as corners and interstices, is completely encased and safe from tampering. Suitable terminals are fitted and are coupled up to a flexible electric cable through which the current is led to energize the coil and to impart the requisite magnetic energy to the lifting face-plate. When the coil is active, naturally the magnet will readily attract any ferrous metal which it may chance to approach, or with which it may come into contact, and this will continue to cling to the face of the magnet until the current is switched off. The magnet is slung upon the hook of the crane either by chains, or bars forming a tripod terminating in a link. It is applicable to any type of crane, whether it be of the locomotive, jib or derrick type or overhead travelling system, and with equal facility.

The foregoing description is merely a bald description of the lifting-magnet in its simplest form. To secure the highest efficiency many perplexing technical issues had to be resolved. The magnet is necessarily of impressive dimensions and weight, circular or rectangular in regard to the form of the face-plate according to the nature of the work to be fulfilled, and ranging from 24 to 62 inches in diameter. The most popular size is that measuring 52 inches across the face. Massive construction is inevitable to enable the appliance to withstand the rough wear and tear, as well as unceremonious handling, to which it is exposed in the average iron-works by indifferently skilled labour, or to meet the conditions of piece-work when operations are necessarily conducted at relatively high pressure by the men who are bent upon the consummation of one end—the maximum return in the form of wages for the work accomplished.

Robust construction involves weight. Precisely what this means may be gathered from the fact that the German 52-inch lifting-magnet weighed 3 tons, whereas its British rival, to which I am referring, weighs only 2¹⁄₂ tons and has a 20 per cent. greater lifting capacity, despite the reduction in weight of the magnet itself. The magnet in question will lift from 900 to 33,600 pounds—even more—according to the character of the material to be handled, the lower figure applying to sheet-iron, scrap, and bolts, while the other extreme refers to heavy solid steel ingots or armour-plate.

Precisely why the lifting-magnet should have taken so long to establish its virtues, both in this country and the United States of America, is somewhat inscrutable, especially in the latter country which, as a rule, is disposed to introduce time-and labour-saving appliances with alacrity. No matter from what point of view it may be regarded, it represents the biggest time-and labour-saver as well as money-maker yet introduced into the steel industry.

One reason advanced for its comparatively slow adoption is rather interesting. It was averred that to the men, accustomed as they were to seeing loads slung by chains, the sight of a mass of steel clinging to the face of the magnet by a force which they could not understand verged on the uncanny. They knew little or nothing about magnets except in the form of a toy, and could not understand that sufficiently attractive effort could be exerted to keep the mass adhering to the flat face of metal. The fact that the moment the current was switched off released the load was something equally beyond their comprehension. Forthwith they arraigned the lifting-magnet as dangerous, and, while not openly condemning its use, declined to work in its vicinity. Whether this was so or not has never been fathomed, but it is generally observable that men working with such an appliance observe a wise discretion, and refrain from working or moving beneath it. This very respect for the apparatus has achieved one distinctly valuable result: accidents are few and far between, even in America, in which country respect for human safety is declared to be at zero, where the handling of huge masses of metal is conducted by the lifting-magnet.

But, eliminating the psychological effect upon the workmen, it is to be feared that employers were slow to visualize its advantages. Certainly in Britain there are many employers, who, notwithstanding the impressive array of figures advanced in its favour, and who have been brought face to face with the economies it is able to effect, still cling tenaciously to antiquated practices.

So far back as 1911 Mr. H. F. Stratton, in drawing the attention of the American Foundrymen’s Association to the possibilities of the lifting-magnet, presented some illuminating figures. At that time the American steel industry was handling 10,000,000 tons annually by this system and thereby was saving over £200,000—$1,000,000—a year. So far as scrap was concerned he emphasized the opportunity it presented in this field, because, out of an annual melt of 6,000,000 tons of pig-iron and scrap, from 1,000,000 to 2,000,000 was represented by scrap-iron and steel.

The American railways were among the first to appreciate the possibilities of the system. The Chicago, Rock Island and Pacific Railroad introduced the idea for handling scrap and iron in 1909. Up to that time all scrap had been handled by hand, the cost in and out ranging from 30 to 35 cents—15d. to 17¹⁄₂d. per ton—which, according to the authority cited, could be accepted as applicable to all the railways following such a practice, and to record which figure, be it noted, demanded excellent arrangements and efficient organization. Upon the introduction of the lifting-magnet these costs were immediately cut down to 10 to 12 cents—5d. to 6d.—per ton, in and out, inclusive of every expense, the figure for the actual sorting being only 4 to 7 cents—2d. to 3¹⁄₂d.—per ton. The authorities of this railway stated that unsorted scrap could be unloaded by means of the magnet for 2 to 5 cents—1d. to 2¹⁄₂d.—per ton, while, if the scrap were sorted, the cost came out ¹⁄₂ to 1¹⁄₂ cents—¹⁄₄d. to ³⁄₄d.—per ton! Similar work conducted by hand labour, according to the previous practice, cost about three times as much.

That the experience of this one railroad was not isolated was proved by the experience of the Lake Shore and Michigan Southern Railroad, which supplied Mr. Stratton with the following comparative figures for other operations incidental to the conduct of its work:—

It will be observed that the handling charges by the magnet were one-half of those by the crane with chains in connection with the locomotive tyres, and one-seventh in the case of the heavy castings, while the advantage over manual effort in the case of the first-named was no less than 32·5 per cent. Little wonder that, during the past nine years, the utilization of the lifting-magnet in connection with the handling of iron and steel in the United States has advanced by huge strides. To-day it constitutes an integral part of the wrecking equipment of every leading American railroad. After the large debris has been cleared up, the lifting-magnet is swept over the ground to pick up nuts, bolts, nails, screws, and any other odds and ends of a ferrous nature which have escaped recovery by the conventional methods.

So far as these islands are concerned, considerable progress has been made during the past five years in regard to its adoption. Extended use has not been confined to the handling of metal in our steel-works, but for the reclamation of iron and steel cargoes which were lost as a result of the German submarine activity. Its employment in the salvage field was suggested as the result of the sinking of a barge carrying ingots of very special steel sunk at the entrance to a port on the East Coast. Although the wreck lay in relatively shallow water, it was speedily discovered that salvage by the orthodox methods would prove somewhat uncertain, owing to the awkward position of the sunken barge and the difficult tidal and other conditions.

The possibility of retrieving the valuable steel by magnet was broached to Mr. F. N. Pickett, the inventor of the British lifting-magnet, to which I have referred. A certain doubt upon the point existed in official circles from the knowledge that the German appliance could not be employed in such duty, owing to the coil not being impervious to water, which of course nullifies the utilization of the electric current. But the British magnet, being built upon different lines, is watertight, and so the designer expressed complete confidence in his apparatus being suited to the task. The magnet was secured, and divers went down to blow open the side of the barge to permit the magnet to reach the cargo.

The magnet was lowered and was found to work with as much ease and simplicity as under conventional conditions in the steel-works. It was plunged into the hold of the invisible craft, and subsequently the sea-bed on either side was swept therewith. So successfully and completely did it fulfil its unusual task that every ingot was retrieved, and that within a very short time. The sinking of the barge occasioned little damage beyond a slight delay in the delivery of the material, which was valued at £150—$750—per ton. True, the barge was lost, but that was an insignificant disaster, and but poor recompense for the expenditure by the enemy of a torpedo costing possibly £1,000—$5,000.

The success of the magnet in this instance has been responsible for its utilization in other fields of submarine endeavour. A freighter was sunk with a valuable steel cargo aboard. The vessel was examined and found to have settled upon an even keel. Divers descended and opened the hatchways, while sections of the decks were cut away to expose the cargo. The magnet was then brought into action, and the cargo unloaded as readily as if moored alongside the dock. This success in the open sea has been responsible for the salvage of similar cargoes which have been lost around our coasts. So far as the Pickett-West lifting-magnet is concerned, there is no obstacle to its use in this field so long as sufficient swing can be imparted to the suspended apparatus to ensure sweeping of the wreck, and up to the depth corresponding to the pressure of the insulation in the coil drum. Seeing that this is introduced at a pressure of 120 pounds to the square inch, the lifting-magnet can be safely used in water up to a depth of approximately 250 feet without the insulation collapsing under the imposed water-pressure, and this is a depth far beyond that at which a diver can work. But, taking the wrecks lying within water accessible to the diver, appreciable recovery should be possible.

It is generally conceded, in view of the success which has already been achieved, that there is a promising future for the apparatus in this field so long as it is designed and constructed along correct lines. The cost of operations will be reduced therewith very materially, and the strain imposed upon human effort as represented by the diver will be decreased very markedly. Instead of salvage operations being confined to an hour or two daily, according to the velocity of the tides and currents, it will be possible to continue work during the round twenty-four hours so long as the weather is propitious. The operator will be able to sweep the wreck from end to end, as well as to scavenge the sea-bed by swinging his magnet, confident in the knowledge that magnetic metal will be trapped in the process for haulage to the surface. Even if ships should prove impossible of recovery intact there is nothing to prevent their reclamation piecemeal. Dynamite will reduce the wreck to scrap of weight and size within the lifting capacity of the apparatus, and at the price obtaining for such junk the expedient should prove profitable. So we should be able to retrieve a certain and imposing proportion of the wanton waste incurred by the ruthless attacks of the enemy upon our sea-going traffic.

It has even been suggested that the magnets might be employed to salvage many of the German submarines which we have sunk, more particularly the coastal type of craft. These were relatively small, and for the most part were sunk in comparatively shallow water. In the water-logged condition the dead load to be handled is approximately 800 tons. If desired these craft could be lifted to the surface intact, or, if in pieces, retrieved in sections for sale as scrap. The inventor has elaborated his plans, which involve the suitable disposition of a certain number of magnets over the sunken submarines. He suggests that eight magnets would be adequate for the task. Seeing that each magnet has a pulling power of 250 pounds per square inch of its surface, the aggregate haul which could be brought to bear upon the submerged craft simultaneously by the eight magnets would be at least 1,920 tons, or twice the total weight of the submarine. With such a lifting effort available it should be possible to drag the wreck from even the extremely tenacious North Sea mud. The question arises, although recovery of such waste is admitted to offer every attraction, as to whether the German submarines are worth the trouble, even if they be sold as scrap. In view of the price which the surrendered boats realized this is extremely doubtful, although experienced salvage engineers admit that even if prevailing scrap prices were obtained the venture would prove profitable, that is in the strict commercial sense.

As a scavenger for magnetic metals the lifting-magnet cannot be excelled. It is far more thorough than hand-labour, and will fulfil its mission more completely than any other mechanically-operated device to this end. Lowered to twenty-four inches of the ground it may be swept, or swung, to and fro in the certain knowledge that any stray scraps of iron and steel will readily jump the intervening space in response to the strong magnetic influence exerted. In this manner a wide area can be completely cleaned of all stray iron and steel fragments, much of which would otherwise be lost within a few moments.

The recognition of the peculiar qualities of magnetic attraction has led to an interesting development which should prove capable of extensive application and to distinct commercial advantage in our steel-works. As is well known, the slag is run off separately to be dumped. But this slag often carries an appreciable quantity of metal in a divided state. Hitherto this has been wasted, but it has been found that, if the slag be broken up, by the aid of a magnet and “skull-cracker” ball, and the magnet be swept over the mass, that the fugitive metal can be retrieved and in sufficient quantities as to render the operation profitable.

For the movement of iron and steel in factories it is difficult to excel. A consignment of kegs of nails, bolts, nuts, screws, or some other small articles requires removal to or from store, or to vehicle. Under normal conditions the practice would be, either to stack them on trolleys or to pack and sling them from cranes, the loading constituting the adverse factor from the appreciable time it takes. If the magnet be used no such preliminaries of any description are necessary. The magnet is merely lowered, the current switched on, and the next moment as many loaded kegs as can squeeze themselves upon the face of the magnet may be lifted. The attractive effort is sufficient to exert its influence through the covers of the kegs to act upon the metal within. Moreover, if the kegs be small, more than one layer will be found possible of removal at a time, inasmuch as the depth to which the magnetic influence can be exerted—“digging” effort as it is called—has been found to be equal to the diameter of the magnet face.

For handling metal waste in the form of turnings or swarf it is far cheaper and quicker than any other known process. When the magnet is dropped upon a pile of such residue and is then raised, it will tear away a huge chunk of the heap—a ton or more of tousled and ragged ribands of steel jostling and clinging tightly to one another and to the magnet-face like a swarm of bees to the branch of a tree. It will successfully handle, and for no heavier cost, swarf which defies handling by any other means, except at prohibitive expense. At a certain steel-works in the North of England ten tons of matted steel turnings were permitted to stand for several weeks in a railway truck in an open siding. When it was decided to unload the vehicle the turnings were found to have rusted and to have settled down into as tightly packed a heap as could be imagined. The normal practice was for men to shovel such material with their forks into the charging boxes, but they found that they could not force their tools into this formidable heap. The mass was surveyed and the hopelessness of coping promptly therewith was admitted. Under manual labour the job would occupy several days, even if it could be successfully handled at all, upon which point considerable doubt prevailed.

It was decided to try the magnet. It was brought along on its traveller and lowered into the truck. The winding drum was set going, and there was a fearful snapping and snarling. The magnet refused to release its hold, while the metal, being tightly jammed and packed, offered a stiff resistance to the irresistible attraction of the magnet. But, within a few moments, the magnet tore itself free with some 3,360 lb. of the tangled rusted steel clinging to its face. Within six minutes, and by half-a-dozen lifts, the vehicle was cleared of its ten tons of scrap.

While the circular form of magnet is that generally favoured, variations are made to comply with different requirements. Some articles, such as steel rails, pipes and iron rods, from their distinctive shape, only present an extremely limited surface upon which the magnetic pull can be exerted. As a rule, to enable such articles to be handled with efficiency and speed, two magnets, rectangular in form, and spaced a short distance apart, are used. The magnets are coupled together, but maintained a specific distance apart by spacing bars, while they work in unison. While the area available for contact upon each magnet is somewhat reduced, as compared with the circular type, this deficiency is counterbalanced by the ability to apply the magnetic lifting effort at two points.

It is doubtful whether the true money-saving possibilities of the lifting-magnet are really appreciated. The initial outlay may appear heavy—in the case of the British magnet to which I have referred it ranges from £150 to £600—$750 to $3,000—according to dimensions, face-form and lifting capacity—but this expense is readily recouped. The lifting-magnet is not only a time-saver but it enables given work to be accomplished with fewer men. In some instances this displacement of labour has attained striking proportions. At one steel-works a lifting-magnet of 52-in. diameter was installed at a cost of £400—$2,000. It is employed for handling pig-iron, and in this work has dispensed with fifty men. The saving in wages, which its introduction has rendered possible, sufficed to defray the capital cost of the apparatus during the first three months of its use.

The results recorded at another establishment are equally impressive. A 36-in. magnet was acquired, and for one specific duty—loading trucks—was employed for a total of twenty hours during the month. Previous to its acquisition this work was carried out by manual labour, and it used to demand the combined efforts of ten men for ten hours to load the vehicle, the cost being £4—$20. With the magnet the truck is now loaded in two hours and at a cost of 8s.—$2—this figure being inclusive of all charges—electric current, depreciation, interest, labour, etc. In the course of the year the magnet puts in 240 hours truck-loading, the number of trucks dealt with during this time being 120. The saving effected by the utilization of the magnet is thus £3 12s.—$18—per truck or £437—$2,185—per year. Seeing that the magnet at the time of its installation cost £150—$750—it will be seen that it pays for itself approximately three times over in the course of each twelve months, and that upon one single range of duty for an insignificant period of time.

Under manual conditions of handling scrap and at the current contract trade union rate the cost is 1s. 4d.—33 cents—per ton. With the lifting-magnet, including labour and depreciation, the cost is only one penny—2 cents—per ton for this work—a reduction of 1s. 3d.—31 cents—per ton! At the works of the Stobie Steel Company, Dunston-on-Tyne, the initial cost of the lifting-magnet was recovered during the first four months it was used. This company declares that the annual saving which its employment effects is £800—$4,000.

But the applications of the magnet are not confined to lifting and carrying operations. As an instrument for breaking up masses of steel too large to be handled conveniently, or to be passed into the cupola of the furnace, it cannot be excelled, either in point of efficiency, safety, or economy. Breaking-up is carried out by what is known as the “skull-cracker,” which comprises a roughly-cast ball of steel which may weigh as much as 22,400, 27,000 or even 36,000 lb. This is picked up by the magnet and lifted to the desired height. The current is then switched off, releasing the ball to fall and to strike the scrap-boiler or some other cumbrous piece of junk a terrific blow.

While the “skull-cracker” has been in vogue for many years with mechanically operated devices, and so is not peculiar to the magnet, yet this latest development represents the highest achievement yet attained in this particular direction. Under mechanical conditions from four to six men are required to carry out the work successfully. With the magnet and ball the task can be fulfilled by two men—if exigencies so demand it can be completed single-handed by the crane-magnet operator—while the time occupied in such essential destruction is very much less, more efficiently accomplished and with complete safety, because under mechanical conditions breaking-up is generally regarded as highly dangerous work. A further advantage is offered by this system. The “skull-cracker” can be lifted and dropped alternately until the scrap has been reduced to suitably sized pieces, and then the magnet, disdaining the ball, can pick up the pieces of junk to bear them away to the furnaces without any delay.

Despite the forward strides which have been made in regard to the adoption of the magnet in the British iron and steel trades during the past four years, this system of handling ferrous metals is still in its infancy. It has been neglected far too long. Yet it is a force which in the future must play an increasing important role, because it is generally admitted that, to offset the higher wages incidental to production, it is imperative for manufacturers to exploit fully every possible time, labour, and money-saving device. The magnet is one of the most attractive contributory factors to this end, especially in connection with the handling of iron and steel waste, that has yet been contrived.