Show THE metallurgy OF LEAD WRITTEN FOR THE MINING REVIEW BY H B E M primitive lead smelting smelling Sm elting it is remarkable with what crude and simple methods lead may be reduced from its rich ores A heap of the ore is surrounded with a strong wood fire and from beneath the ashes flows out a stream of liquid lead better yet rich lead ore is thrown into a mass of glowing coals and burning wood and the same result follows a goodly amount of metallic lead is formed it remains moulten from the heat and flowing out from beneath the fire can readily be collected after we have studied the chemistry of I 1 described than the early smelting smelling sm elting in any other land in certain parts of india the natives still reduce lead ores on a small scale with the use of bellows a process doubtless handed down from great antiquity a method of smelting smelling sm elting was also in use in peru which resembled the method used in britain which may now be described in his history of lead quotes camden who in describing the lead deposits of derbyshire writes as follows for in these mountains fertile lead stones are daily up in great abundance which upon the hilltops hill tops lying open to the west winde 1 s IMM MININ 4 the smelter near utah now idle lead and its compounds the reactions involved will seem simple enough it will be seen that this rough fire test Is but a loose way of carrying out these same processes by which with modern knowledge experience and equipment we can make a close and economical saving of the lead in any ore the fact which we now especially desire to fully realize is that the abundance of lead ores and their easy production has given the metal far more of a standing than its uses justified the way to smelt it must have been stumbled upon often enough by more intelligent races long considered the basest and most abject of all the metals its usefulness was slight in comparison to the ease with which it could be obtained other metals highly esteemed were little available either because of their rarity or the difficulty of winning them from their ores it is likely that the primitive is melting as once practiced in britain is more accurately nere unto creach and worthe which hereupon took the name of the lead when the we sterne winde ginnes beginner be to blow which winde of all others they have by experience found to hold longest they melt with mighty great fires of wood into lead in troughs or trenches which they bigge of purpose for it to runne into and so make it up into 11 dr percy gives a few paragraphs relating to this sort of smelting smelling sm elting in his metallurgy of lead which was published in 1870 they are so concise that we may quote them as they stand bishop watson in his elegantly and lucidly composed chemical essays which I 1 never take up but with increased pleasure has treated of the smelting smelling Sm elting of lead ore as practiced in derbyshire he says there are several places in derbyshire called boles by the inhabitants where lead has been anciently smelted smelter smelt ed before the invention of moving bellows by water these places are discovered by the flags of lead which are found near them there Is no certain tradition concerning the manner in which the ore was smelted smelter at these boles it was probably as simple as that of the peruvians for in derbyshire as well as in peru they seem chiefly to have relied upon the strength of the wind for the success of the operation the boles being always situated upon high grounds and mostly upon the side of a hill which faces the west this situation was not fixed upon without design since the wind blows in england in the course of a year near twice as many days from that quarter as from any other watson quotes an author of the seventeenth century joshua childrey D D to show that lead smelting smelling in derbyshire was conducted in this rude way so late as that period the lead stones in the peak writes the doctor lye but just within the ground next to the upper crust of the earth they melt the lead upon the top of the hills that lye open to the west making their fires to melt it as soon as the west wind begins to blow which wind by long experience they find holds longest of all others but for what reason I 1 know not since I 1 should think lead the easiest of all metals to melt they make their fires extraordinarily great the language of the first sentence is much like that of pliny previously cited namely ferrae corio the authority for the foregoing statement concerning the practice of the peruvians is alonzo barbe a spanish priest and eminent metallurgist of the seventeenth century the natives of peru he says not yet having bellows to use employ furnaces in smelting smelling sm elting which they call gu airas and which they still employ these gual ras resemble castillian furnaces they only differ from them in being filled on all asides with holes t through which the air enters when the wind blows which is the only time that metal can be smelted smelt ed it comes out at the lower part from each of these holes like little ears where there is charcoal on the outside in order that the air may enter hot these furnaces are placed in high situations and where there is most air at the present day furnaces constructed on a similar principle have recently been in operation in the south of spain for the smelting smelling sm elting of certain kinds of poor lead ore but in which the draught has been produced by a chimney 11 biales Bi oles also termed bayle hills are stated to in the mining districts of northumberland cumberland and durham as well as in derbyshire according to forster they were simply piles of stones placed around a fire on the western brow of an eminence and so arranged as to leave openings which served for the admission of air and the escape of the gaseous products of combustion fuel was supplied from the neighboring woods which on that account were called hag hill or hag bank already by 1678 the scarcity of wood for fuel in eno england land had forced an improved method in the smelting smelling sm elting of lead in this year were granted letters patent smelting smelling sm elting with pit or sea coal in close or furnaces the old type of smelting smelling sm elting persisted longer in germany where wood was more plentiful agricola gives descriptions of furnaces used in north italy and in saxony these were small and more like the furnaces which the romans mostly used in westphalia the open furnaces such as those used in britain were commonly employed travelers passing through parts of asia in japan and india have observed the little furnaces with which the natives work up small lots of ore these furnaces are usually ur urged 0 ed with bellows and not unlikely practically the same as those used for centuries percy furnishes a few details as to one of these furnaces which was seen by captain dixon near aamir in india and described by him in 1831 the diameter of the furnace at the top was eleven inches at the bottom ten inches it was three feet high three rather angular clay nozzles were to the base and admitted the blast of air supplied by three bellows made of goatskin goat skin and worked each by a man through the nozzle a hole allowed the interior to be seen and permitted cleaning and stirring A tap hole five inches up from the bottom served for tapping the slag and another in the very bottom of the furnace emptied it of lead this furnace required some seme over one half the weight of the lead produced in charcoal for fuel fine ore made into balls with dung and dried was fed alternately with the layers of charcoal in nine working hours the output averaged between and pounds of lead at an average extraction of some 40 per cent A crude method of smelting smelling sm elting evidently borrowed from the indians prevailed for many years at the lead mines in missouri it is a matter of history that one of le party by name Peni discovered lead in the eastern missouri district in the year 1700 mine aline la motte began to be extensively ten exploited in 1715 from this time until after 1800 the so called log furnaces were the chief means of smelting smelling sm elting the product of the mines indeed the log furnace survived even longer some were in use until 1850 it was about 1840 when the introduction of the scotch hearth took place extensively ten that this crude sort of furnace began to be abandoned in his book entitled lead and zinc in the united states W R ingalls gives us a good insight as to the manner of this smelt ing the ore cleaned of clay by hand was smelted smelter either on log heaps or in a rude construction known as the log furnace according to schoolcraft this furnace was built against the side of a hill sloping about 45 degrees three large oak logs were rolled into the furnace transversely resting on the ledges at the sides small split logs were set up vertically around the inside of the furnace after which about pounds of ore in pieces averaging fifteen pounds weight were piled up in the furnace covered with logs and the fire started the method of smelting smelling sm elting which was lead smelling smelting in almost the most primitive manner is to be classed as a roast reaction process the fire was kept low for about twelve hours during which the roasting took place A stronger heat was vas then maintained for twelve hours more to effect the reaction during which period lead trickled out into a basin in front of the furnace sometimes the reaction period would have to be extended to twenty four hours this depending largely upon the skill of the smelter As may be imagined the extraction of lead by this crude process was very imperfect if we may judge from the ore obtained nowadays from similar deposits the grade of the mineral early won was likely upward of 80 per cent lead or 1600 pounds per ton the yield of lead from a ton con of ore smelted smelter in the log furnace was only to pounds or less than 50 per cent of the lead in the ore by the methods of smelting smelling sm elting now in use an extraction of 98 per cent of the lead is attainable in 1799 a man by the name of austin entered the missouri smelting smelling sm elting field he brought in ideas of his own and soon made a 9 considerable improvement in the recovery of lead his furnace was more like a ber atory but had a sloping hearth it was made of limestone and lasted only between two and three weeks after which it had to bo be reconstructed it was known as an ash furnace in this furnace the residues from the log furnaces could be again smelted smelter a recovery of 15 per cent more metal As the furnace did not cost much to rebuild it soon supplanted the former log furnace in 1797 about twenty log furnaces were running about potosi in 1802 only one remained active the rest preferring to let austin do the smelting smelling sm elting for them it seems that not all of the furnaces were even as well constructed as the log furnace just described others rather resembled an open limekiln stones surrounding the fire on which was wag heaped the ore it in turn covered with abundant fuel with all this enormous waste of fuel and metal the method still persisted until after 1850 little by little giving ground to the ore hearth and later the old slag dumps were smelted smelter to good advantage in the new type of furnaces H 13 armour institute of technology chicago ill 0 |