| Industry. | Material Treated. | Quantity. | Oil Recovered. | Per Cent. |
|---|---|---|---|---|
| Pints. | ||||
| Agricultural machinery | Cotton-waste | 18 lb. | 9·75 | 54·16 |
| Biscuit manufacture | Cotton-waste[1] | 10 lb. | 4 | 40 |
| Colliery | Cotton-waste[2] | 39.75 lb. | 63 | 158·69 |
| Cotton-waste[3] | 15·75 lb. | 10 | 57·5 | |
| Cycle and parts | Rags | 112 lb. | 80 | 71·42 |
| Sponge cloths | 1 gross | 8 | — | |
| Foundry | Cotton-waste | 13 lb. | 11.25 | 86·53 |
| Machine-tool manufacture | Cotton-waste | 8·25 lb. | 2·75 | 33·33 |
| Motor-car | Cotton-waste | 16 lb. | 1·25 | 7·81 |
| Rags | 12 lb. | 2·75 | 22·91 | |
| Railway | Cotton-waste | 14 lb. | 2·625 | 13·75 |
| Cotton-waste[4] | 10 lb. | 13 | 130 | |
| Steel and iron-works | Cotton-waste | 8·25 lb. | 9·25 | 112·12 |
| Mutton cloths | 2 lb. | 1·5 | 75 | |
| Tramway | Cotton-waste | 13 lb. | 1·25 | 9·61 |
| Wood screw manufacture | Cotton-waste | 21 lb. | 13·75 | 65·47 |
But so far as industrial operations are concerned oil reclamation is by no means confined to the treatment of the waste and cloths. As already mentioned, oil is freely used in working metal, acting as the lubricant to the cutting tool. While trough facilities are provided to catch the oil to enable it to be used again, much clings to the turnings and other refuse. Even where works are not equipped with oil-recovery apparatus of some description or another an attempt to secure a proportion of what would otherwise be lost is made. The turnings are permitted to drain. The quantity of oil recovered in this manner, however, is very low. Certainly it does not exceed 40 per cent., because the oil clings somewhat readily and freely to the metallic surface.
Accordingly, in the best equipped factories, the practice is to submit the turnings to treatment. It is passed through the extractors and in this way at least all but 10 per cent. of the oil is recovered. When the solvent extraction process is exploited the recovery can be carried as far as 99 per cent., the fraction resisting recovery thus being extremely small. The yield obtainable from such metallic residue from the machines is certainly sufficient to justify the treatment. In one shop, devoted to the manufacture of cycles and cycle parts, the oil recovery averaged 22 pints per 112 lb. of turnings treated. In another instance, where the production of agricultural machinery is conducted, 26 lb. of steel turnings and 23 lb. 9 oz. of brass turnings yielded 1·75 and 1·125 pints of oil respectively. One motor-car manufacturing firm recovers 1,200 gallons of cutting oil from the treatment of its weekly accumulation of turnings. This becomes available for re-use, and the absolute loss recorded is only about 10 per cent. In another instance, 2,440 gallons of oil were recovered from the treatment of 41 tons 17 cwt. of metal turnings, 900 lb. of rags, and 19,300 sponge cloths in the course of six months.
Another interesting experience in this field is worthy of record. It was found that the sawdust in the vicinity of certain machines, provided as an absorbent, became somewhat heavily charged with oil splashed and otherwise discharged from the machines. The presence of the oil-soaked refuse on the floor was construed as being a menace to the establishment, the hazard of fire being regarded as thereby increased. Accordingly, the floor was swept more frequently than otherwise would have been the case, the refuse being promptly shovelled into the furnace merely to secure its prompt and complete riddance. The sawdust was examined by a waste expert upon the occasion of a visit to the works, and he suggested, from the fact that oil oozed from a handful of the sawdust when squeezed, that the waste should be subjected to the “Iwel” oil-reclamation process, instead of being burned. The recommendation was followed, and the volume of oil thus recovered was found to be of surprising quantity. In fact, its value more than defrayed the cost of the small plant which was installed to treat it. So effectively was the sawdust found to be cleaned of the oil as to be redistributed time after time upon the floor around the machines. In this instance destruction of the oil-soaked refuse by fire represented a material loss in more senses than one.
While it is only within the past few years that the possibility of reclaiming oil from cotton-waste has aroused such earnest attention, it must be acknowledged that many firms sought to reduce their expenditure by submitting their cloths and waste to a laundrying process. Of course, by this practice the textiles were recovered, but the oil was lost, while material expense was incurred in the conduct of the laundrying operations and the acquisition of suitable detergents. An interesting record of the cost of the respective processes is forthcoming from a certain firm in the South of England. It refers to two years’ operations, the one referring to straight laundrying of the sponge cloths and waste, while the other refers to the latest method of dealing with such materials. Under the former régime the cost for the year was £219 9s. 2d.—$1,097.28. The heaviest items were for the purchase of sponge cloths and waste, the figures for which were £62 17s. and £137—$314.25 and $685—respectively. The cost of washing the dirty cloths at 7s. 3d.—$1.78—per week was £18 17s.—$94.25.
The firm then acquired a small oil reclamation and cloths-cleaning plant at a cost of £125—$625. During the year, under the new conditions, the expenditure on account of sponge cloths and waste was £25 16s. and £85 15s.—$129 and $428.75—respectively, but, for purposes of comparison, one-fifth was added to each item to counteract the slackness encountered, and to bring the subject more in line with the experience of the previous year. But even after making these allowances the total expenditure for these two articles came out at only £133 17s. 2d.—$669.28—against £199 17s.—$999.25—when the textiles were laundered. Inclusive of all expenditure, including wages, washing materials, power, and interest at 5 per cent. upon the first cost of the plant, the total cost was £199 4s. 4d.—$996.8—as compared with £219 9s. 2d.—$1,097.28—for the previous year—a saving of £20 4s. 10d.—$101.20. But under the new system 716 gallons of oil, totally lost under the previous method, were reclaimed, which represented £11 15s.—$58.75, so that the total saving was £31 19s. 10d.—$159.98, representing approximately 25 per cent. on the capital outlay incurred for the installation of the plant.
In view of the economies possible from the practice of such a system as I have described, it is somewhat surprising that manufacturing firms should hesitate to include an oil-reclamation plant in the equipment of their establishments. It is likewise somewhat difficult to bring home to them what really can be achieved by the scientific treatment of their waste. In order to popularize the practice, and to further the observance of economies which are inseparable from industrial operations under contemporary conditions, more than one British firm is prepared to advance an attractive commercial proposal. This is that the equipment should be installed and its cost defrayed out of the actual savings effected. Thus, in the case of the installation to which I have made reference, and which deals with the rags accumulating from the maintenance of public service vehicles, such a procedure was initiated. The capital expenditure involved in this instance was approximately £2,200—$11,000, but as the plant recorded a net saving of £450—$2,250—as a result of three months’ work, which is equivalent to £1,800—$9,000—a year, it should be able to defray the whole of the initial outlay within about 16 months. However, all things being equal, it is computed that a reclamation plant submitted to the work which I have described should pay for itself within two years. Experience serves to support this contention, although, under the conditions which at present prevail, the possibility is that such a gratifying achievement would be fulfilled within a shorter period.
FOOTNOTES:
[1] From engine-room.
[2] From blast-furnaces.