| Show new process of zinc smelting smelling Sm elting employs liquid hydrocarbon the established methods have a flexibility characteristic of processes which have evolved slowly and it has usually been found in practice that by introducing such modifications as local and peculiar circumstances demand they can cah readily the art of extracting the common metals from their ores has now reached such a state of efficiency that no very profound changes in principle are likely to arise for a considerable sid iid erable time according to the ironmonger of london be adapted to the purpose of a wide range of raw material the recent development and cheapening of electrolytic and other methods of refining b has fu further arther tended to consolidate the position of the standard processes for the production of crude metal perhaps the least satisfactory of the commercial metals in this respect i is zinc the met metallurgy allergy of which has long called for attention I 1 mechanical and minor metallurgical improvements appear to have done all they can for zinc zinc smelting smelling sm elting without removing the inherent difficulties of extraction the problem is not only technical albut but also economic not only a matter of obtaining better control of working conditions and insuring goad 0 o od yields but also one of reducing the cost of extraction the difficulties referred to have naturally had the ef feet hect of driving darivin modern zinc production into a groove tend mg to restrict the working of all but the richer and less complex ores to the neglect of a variety of second rate materials less amenable to present methods of extraction but by no means negligible as sources of the metal broadly B y the typical present day process of zinc extraction e consists in roasting the ore ora if it be of the sulphide blende blen e variety or calci ning 6 it if of the carbonate carbond te calamine class and reducing the oxide thus obtained by beatin heating t mixed with coal in retorts and condensing the zinc vapor there alier e was obviously no practicable way of avoiding either of these processes of roasting and reduction both of which involved ned a heavy consumption of fuel and a good bod deal of skilled d intention it attention these considerations have been in in great measure responsible for the inordinate size of zinc smelting smelling plants and the high labor and fuel costs which discourage the smelter and lead him to regard an exceptionally small margin of profit as inevitable and inseparable from the industry coley process to the rescue it is therefore theredo re an advance of the greatest importance which has been made b by H edwin coley who has success uly hilly divelo developed ped a process in which the r reduction is obtained by the use of a liquid hydrocarbon mr coley who fist st put his idea to erp experimental arim test some four years ago hi as now brought brou this new method of zinc smelting smelling sm elting to the stage age of full scale operation and the results r fulfs of prolonged working have brov proved i ed the substantial nature of its advantages the element of the furnace is a rotating tube sported supported at a slight inclination to the horizontal on roller bearings and so designed that with a suitable speed of daiv g th e charge is worked through it its s whole length of 30 feet aln about three hours surrounding the tube is a brickwork structure provided with a regenerative system for burn in 9 producer gas and thus maintaining the high temperature necessary for reduction and volatilize volatilization tion of the zinc the raw ore having been screened 34 in mesh is is continually fed from a hopper to the a short tubular camber cb aniber and passes through it at the rate of half a ton an 01 shaft connecting the eventually falling into a vertical pheater with the main mai n t tube u be the pe partially roasted ore is is raised by means ot of a mecha me scoop coop and fed to the mouth of the main niam tube through which it is is propelled by the combined action of the turning of the cylinder and the annular vanes which are spaced at intervals along the inner surface thus the ore passes in timeto time to the reduction end of the furnace here in the form of zinc oxide and in a porous con condition it is is brought into contact with heavy oil which is directed upon it from a nozzle essential novelty of the coley furnace it t is at this stage that the essential novelty of the cole coley fur furnace nace is i encountered for it is mainly on the peculiar method of introducing the hydrocarbon to the heated oxide that th the e success success of the process depends it ha has already been said that the use of liquid hydrocarbon as a reducing agent for zinc oxide had been attempted previously ioury but the conditions governing this reduction i reaction were no not t fully understood and the results were e disappointing p antin mr 1 coleas solution lution of this problem was wa s a 10 logical kp i at consequence of his grasp of the mechanism of oxidation afo il by means means of so solid lid carbon by taking the hydrocarbon to the reduction zone and delivering it cold to the heated oxide it was found that the carbon was made available in the transient condition of nascence which is characterized by extraordinary chemical activity whereas in previous attempts to utilize a liquid hydrocarbon as the reducing agent the oil at the high temperature prevailing in its furnace was decompo sedor cracked before its maximum reducing 6 effect could be secured mr coley by employing the oil cold insures the liberation of the carbon in intimate contact with the zinc oxide and under the critical circumstances which give ive rise to the nascent stale the hydrocarbon is brought to the reduction ind end of th the e fu 1 nace by a pipe passing through the axis of the main tube and directed upon theovide the oxide by means of a water wate r co cooled oled nozzle Z 1 e aio another afier interesting feature of the new process is that the I 1 nas nascent camf carbon exer exercises cies its it enhanced reducing power at a temperature considerably lower than 1400 C required under no normal amal conditions indeed in the experimental furnace n ace th this I 1 is maxi maximum I 1 mum reducing effect was attained at a temperature pera ture 6 of abut about 1000 C volatilization and water cooling aa 4 the liberated zinc volatilizes ola tili z es and passes through gha a connecting necking shaft to the condenser a water cooled cha chamber i mb i where the metallic va vapor p or is is c condensed while the accompanying gases pass on the solid residue is continuously ejected at the end of the tube and is abai available able for treatment nt meef feht for the tha recovery of lead silver etc in the usual way I 1 the outstanding advantages which the new process offers will be apparent from what has already been stated the initial cost of the plant is estimated at not mor ethan a unit compared with about under exis existing smelting smelling sm elting conditions the economy in fuel and labor represent a very material a I 1 saving three men are capable of ape operating a furnace unit as against the ten to fifteen required bequir ed on the complicated plant of the established process the effect of the econome economies es is is reflect reflected ed in the cost of production which third to one half of the than one is claimed to fo be no greater which naturally varies in different present cost coat of production countries remarkable smelting smelling Sm elting efficiency another factor materially responsible for this result is ig the remarkably high smelting smelling sm elting efficiency of the new pro process cessy yield of 0 ver over 95 per cent ift m the which is stated to give a working of ordinary blende ores under full scale conditi conditions on moreover the process is applicable to ores that differ widely in composition and is capable of accommodating carbonate and silicate ores as well as blend one of the test runs of the new furnace was conducted on a low grade calamine assaying only 19 per cent of zinc with highly satisfactory results in normal working a contributory tribu tory factory to the low cost of production is the yield of lead silver etc from the treatment of the furnace residues which are said to be peculiarly adaptable at the moment the new process is being submitted to further commercial tests in the works of stewart lloyds at halesowen Hales owen near birmingham this full scale furnace unit is the outcome of four years of experiment one by one the experimental problems have been worked out and the N C metal company has now definitely acquired the english rights and has also secured an option on the world rights and a company is in process of formation with the object of beginning production in this country from what has been said the significance of this new departure e in the extraction of zinc will be appreciated and if the exceedingly promising results obtained up to the present are are borne out in subsequent industrial working the effects will be little short of revolutionary it would seem that liquid hydrocarbon reduction could be used with other metals and it is not unlikely that in the coley process lies the germ of an important technical principle which may yet be embodied in the metallurgy of iron |
