Volume 08 (1864) (474 pages)

The Mining und Scientific Press, Augustin’s Method of Extracting Silver from its Ores by the Uso of Salt. The following is the most full and intelligible doseription nf Augustin'’s Method of Extracting Silver with Sult Water, whielt we recollect to have met with. ‘Phis description was written at Puris, in Deeember, 1860, by Dr. R. UL. Lauiborn. No metallurgic process springs like Minerva full grown and pertect frum the brain of tho inventor. Muny years of experience, nud the labor of many vigorous minds, have been neeessary to bring somo of our simplest proeesses to the efficient eondition in which we find them. ‘he method of Augustin, although it is sometimes cousidered ns having inangurated a new cra in the treatment of silver ores, forms no exception to the general role. It has a genvalogy a3 long as that of a peer, which if any space permitted it would be interesting to trace back step by step. JT irst to the system of amalgamuting the eopper nintte. a long time in use at Mansfield, with which it has several points of resemblance, then to the Kuropean plan of ainalgamation iu easks, as introduecd by Gellert at the Freiberg works in 1790, then back a decenuium to the region at Schemuitz, where Born amalgamated I[ungarian ares in eopper kettles, afterwards—a loug step—tn the eordilleras of South America were Bartholomé de Medina, in the middle years of the fifteentb eentury invented the American system of amalgumation in heaps. ‘This extended investigution would, however, be incousiztent with my present ohjeet, and hence we will pass at once to aconsideration of the method of Angustine as is at present in use. The European plan of amalgamation, as is well known, consists of three chief processes. 1st. Converting the silver in the ore or product into ehloride, by rousting. 2d. DVecomposing this ehloride and dissolving the silver produced in quicksilver. 3d. Hyaporating the quicksilver aud thus obtaining the silver in an isolated condition. Augustine retnined the chlorizing rnasting and introdueed a new solvent in-place of the expensive quicksilver, and a new plan for obtaining the silver in # separate condition. It is a fact long known to ehemists, and, I believe, first noticed by Wetzler, who reeorded it simply for its seientific value, thut common salt when dissolved in water forma a fluid that has the power of taking chloride of silver into solution. a power that pure water docs not possess in the slightest degree. ‘The amouut of chloride of silver that brine will take up has been made a subject of investigation by modern experimenters, and it has been discovered to depend upon the quantity of salt present and the temperature. ‘Thus at 32° an almost insensible amount is dissolved, at 50° 0.0017 of the weight of cominon salt preseut will be taken up, aud at 212° its capaeity has inereased to 0.0668 of the salt in the brine. Upon this strauge property of salt water rests the fact that the ocean is a vast reservoir of silver, eontaining, aceording to the eareful experiments and ealeulations of French cbemists, not less than 2,000,000 of tons of the precious metal. Upon this same property of salt water rests the metallurgic process introduced by Angustin. Jn outline it consists :-— 1st. In preparing the ore or product containing the silver, for roasting, by grinding it to a fine powder, and then subjecting this powder to treatment in a reverberatory fnruace with an addition of coumon salt, by which means thio silyer is converted into a chloride. 2d. In dissolving the ebloride of silver iu the roasted ore by means of hot concentrated brine and conveying it iu solution to proper vessels for precipitatiou. 3d. In preeipitating the precious metal in the form of cement silver by the ageney of metallic eopper, and in refining the silver so produeed, for the inint. ‘ At Freiberg, in Saxony, where I had an opportunity of studying this method practically, it is employed for extracting silver from a rich copper maite, that is obtained from enpreons silver ores in the course of the peculiar treatiaent knowu as “eommon lead snielting.” The cupola furnaces produce, beside the rich lend, which is sent to the process of cupelling, a sulphide of lead, iron, copper. silver, &e., which is concentrated by repeated fusions until most of the lead has been eollected as rich lead, most nf the iron passed into tho slag, and a sulphide of eopper, iron und silver obtained, whieh in the year 185 contained an nverage of 69 per cent. of the first named metal, and 0.42 per eent. of the last. This matte or regulus is broken into fragments by hand, and pounded to a fine powder beneath aseries of heavy iron stamps. It is now carefully sifted through a brass sieve containing 2500 apertures to the square ineh, and is in a condition to be submittod to tbe process of roasting. ‘The furnaee is of the eommon reverberatory elass, bnt much smaller than those used in Manslield by Ziervogel. ‘The fuel employed is sinne coal, and one attendant is suflicient to carry on the work. Four hundred weight of mineral nre placed on tho hearth at onee, and the fire gradually inereased in strength while the attendant stirs coutinnally, and oceasionally turns the charge eutircly in the furnace, that overy pnrt may be exposed to an intense heat. At the a} of nbout cight luurs the proofs nf complete roasting begin to nppenr; the powder becomes brown and eartliy, the heat does not produee that interior glow which is an evidence of tho presenee of sulphur, nud no fumes ef sulpburous acid are to be perceived. ‘hen the eontents of the fimace are drawn out, allowed to enol. and earried to a mill resembling that usnolly employed for grinding eor:, and after being ground and bolted is brought back to the furnace to be subjected to the ehlorizing rousting. The eopper and iron of the regnlns exist now partly in the form of sulphates, while tho silver is present as a sulphate or in 2 1actallic conditivu. The powder is placed in the same fnrsaee, iu charges of three hundred weight, and roasted for a short time, then mixed witb five per cent. of common salt, and the heat and stirring eontinued for about three hours. During this time the chloride of sodium, or salt, is deeomposed by the sulphuric acid uf the sulphides, ane the free chlorine thus formed combines with the silver, for whieh it has a strong affinity, until, nearly if not quite oll of the valuable metal has taken the form of a chloride. Vhe powder is now drown froin the furnaee and carried in iron trays to the department devoted to lixiviation. ‘This is an elevated room eontaining a number of strongly made, round wooden vessels rauged in a manner siinilar to those at Wettstedt, which have already been described, in rows one above the other, so that the fluid poured in at the upper level will deseend step by step to the bottom. Besides the vessels alarge vat at a still bigher level holds the store of hot brine, which is heated to the proper temperature hy passing steam through it. igbt of the above mentioned tubs occupy the upper row, and in these the dissolving of the ehlorine of silver takes place. The powder, still warin from the furnace, is plaeed in each to the amount of Gewt., and the hot brine allowed to run in upon it. The fluid passing through the mineral mass comes in contact with the fine partieles of ebloride of silver, tukes this compound into solution and carries it through a filter of linen and straw that forms a false bottom of the tub, and thence by tronghs into two reservoirs, whiere the earthy particles mechanically suspended in tho fluid are allowed to settle. ‘Phe process of lixiviation is continued for each tub of powdered mineral, until a bright copper plate, placed in the steam flowing through tho filter shows no indications of n silver precipitate. The solution of the precious metal is now assunied to be as eomplete as possible for the present, and the contents of the tubs are assayed, that the amount of silver remaining may be determined, and that no loss from unpereeived neeidents in roasting nr dissolving may occur. Wheu more than one thirty-third per cent. remains, the powder is again sent to the furnace, roasted with salt, and subjected to another treatment with brine, as above described. If contaning less than one thirty-third of a per cent., which is generally the case, it is enrried to the appropriate furnaces and fusod fir copper. The argeutiferous brine Howing from the lixiviating tabs, after being allowed to deposit the partieles that may be held in mechanieal suspension, passes into three tubs, each containing a layer of eement eopper eight or ten inches deep. ‘The superior attraction of copper for chlorine causes the silver to he precipitated ina reguline eondition as cement silver, while the former metal is taken into solution in its plaee, and carried forward into a fourth range of tubs, where, in order tbat the coniplcte precipitation of the silver may be secured, the brine is brought the second time into contact with fincly divided copper. A still lower range of tubs receives the fluid which now holds much copper in solution, aud where, by means of inetallic iron, the copper is in its turn precipitatedin the form of cement eopper. 'Vhe fluid passes into other vessels eontaiuing iron, that it may be eompletely freed from its copper, and then flows into a reservoir benenth the floor of the apartment, and is finally ppmped into the reservoir spoken of in the commencement of the description, to be heated and passed again over the argentiferous owder, The silver falling in tho precipitation tubs is collected every eight or ten days, clenred of particles of copper by passing hydrochlorie acid over it and placed in a vat where for a period of twenty or thirty days it is allowed to remain in pure water, which is occasionally renewed. It is thon placod in an iron pan upon the top of the furnaco and allowed to dry, and finally, it is eartied to the refluing department, where it is fused and purified. 227. Not only is the separation of the silver more eoinplete than by the method of liquation formerly in use, but the copper obtained by smelting the lixiViuted remnainders is fond to be nach superior to that obtained by the nnetent method, since daring the complete roasting at the Legiming of the process, & greater part of tho ontimony and arseni¢ arn driven off into the atanosphere. Rock Springs District--Colorado, Mining in the Colorado region is in nowise confined to the eountry adjacent to the river. ‘There is every reason to believe that tho entire eonntry between tlnt river and the eoast, and indefinitely to tho eastward, will be found ricb in mines nf gold, silver andeopper. Wherever prospectors have started in, they appear almost invariably to meet with suecess. The Roek Spring district, abont 50 miles frou El Dorado Canon, on the road theuee to Los Angeles, is already beginning to assume eonsiderablo importance. So extensive have these mines becomo that the miners m that neighborhood have found it neeessary to divide the distriet, and n new one has reeently beeu formed from the northerly portion, and named “ Macedonia District.” Roek Spring Distriet is five miles square, hnvitig Silver Ilill for its eenter, while Macedonia Iiill has been fixed as the center of the district of that name. In the latter, work has been actively commeneed in the Mncedonian lode and the Blus Ophir. ‘The Mammoth Company, in Rock Spriug District, aro pushing ahead vigorously with their tunnel. ‘This is said to present an immense lode at its outcrop, and is likely to he very valuablo. An assay recently mado from what is supposed to be a narrow spur, struck in the tunnel, yielded $540 to the ton. ‘Tbe rock from the croppings has assayed at n iuueh higber figure. This tunnel is being driven through very hard gronite. The shaft of the Pride of the Union was down about 70 feet at tho time our informant passed that way, and tho company were taking out some very fine-looking ore. A contract has heen giveu out for sinking a shaft on the Montezuma lode. The Macedonian cry is heard from these mines, “Come over nnd help us!” ‘There is room euough for all who come with means to locate and develop the miues. Companies in this city who are sending men there with hnolf means, however, nre making a great mistake. Thero are uo placer mines tbero from whieh a temporary support ean he derived; neither are there any mills as yet for crusbing and taking the bullion from the ore. The developments are already sufficient to warrant the putting np of a small prspecting millin this neighborhood, say on the road at the Rock Springs Camp, which would be central. Why do not the companies in this eity interested in these mines unite in an enterprise of this kind? If such a project should bo committed to proper hands it would not only be a paying investment, but demoustrate at once, and at small aggregate cost, the value of tho distriet. A mill put up aud run on this plan will save to the miners the extortionate charges of n speculating company, whnse aim is too often to ruin the reputation of a mining neighlorhood, in order to freezo out the locators and buy up their claims for a song. Assays have already shown that silver exists there in large quantities in “specimens,” and the pick nnd shovel bave proven that the lodes are heavy and continuous. We hope soon to be able to reeord the fact that the maehinery bas left this city for a mill for Rock Springs. ‘There is plenty of wood in the neighborhond for fnel and timbering, and thousands of acres of the best quality of mountain bunch grass. Screntiric Sacrinece.—It is said that the French Commission, under the direction of M. de Saulay, is rifling the tombs of tbe prophets and exhuming tho remains of venerated Israelites, to enrich tho seientific eollections at Paris. Many of our Israclitiah friends are much aggrieved at this sacrilege, and justly urge thnt zeal for science should ucver infringe upj-on subjects justly held sacred. ‘ ®

The Mining und Scientific Press, Augustin’s Method of Extracting Silver from its Ores by the Uso of Salt. The following is the most full and intelligible doseription nf Augustin'’s Method of Extracting Silver with Sult Water, whielt we recollect to have met with. ‘Phis description was written at Puris, in Deeember, 1860, by Dr. R. UL. Lauiborn. No metallurgic process springs like Minerva full grown and pertect frum the brain of tho inventor. Muny years of experience, nud the labor of many vigorous minds, have been neeessary to bring somo of our simplest proeesses to the efficient eondition in which we find them. ‘he method of Augustin, although it is sometimes cousidered ns having inangurated a new cra in the treatment of silver ores, forms no exception to the general role. It has a genvalogy a3 long as that of a peer, which if any space permitted it would be interesting to trace back step by step. JT irst to the system of amalgamuting the eopper nintte. a long time in use at Mansfield, with which it has several points of resemblance, then to the Kuropean plan of ainalgamation iu easks, as introduecd by Gellert at the Freiberg works in 1790, then back a decenuium to the region at Schemuitz, where Born amalgamated I[ungarian ares in eopper kettles, afterwards—a loug step—tn the eordilleras of South America were Bartholomé de Medina, in the middle years of the fifteentb eentury invented the American system of amalgumation in heaps. ‘This extended investigution would, however, be incousiztent with my present ohjeet, and hence we will pass at once to aconsideration of the method of Angustine as is at present in use. The European plan of amalgamation, as is well known, consists of three chief processes. 1st. Converting the silver in the ore or product into ehloride, by rousting. 2d. DVecomposing this ehloride and dissolving the silver produced in quicksilver. 3d. Hyaporating the quicksilver aud thus obtaining the silver in an isolated condition. Augustine retnined the chlorizing rnasting and introdueed a new solvent in-place of the expensive quicksilver, and a new plan for obtaining the silver in # separate condition. It is a fact long known to ehemists, and, I believe, first noticed by Wetzler, who reeorded it simply for its seientific value, thut common salt when dissolved in water forma a fluid that has the power of taking chloride of silver into solution. a power that pure water docs not possess in the slightest degree. ‘The amouut of chloride of silver that brine will take up has been made a subject of investigation by modern experimenters, and it has been discovered to depend upon the quantity of salt present and the temperature. ‘Thus at 32° an almost insensible amount is dissolved, at 50° 0.0017 of the weight of cominon salt preseut will be taken up, aud at 212° its capaeity has inereased to 0.0668 of the salt in the brine. Upon this strauge property of salt water rests the fact that the ocean is a vast reservoir of silver, eontaining, aceording to the eareful experiments and ealeulations of French cbemists, not less than 2,000,000 of tons of the precious metal. Upon this same property of salt water rests the metallurgic process introduced by Angustin. Jn outline it consists :-— 1st. In preparing the ore or product containing the silver, for roasting, by grinding it to a fine powder, and then subjecting this powder to treatment in a reverberatory fnruace with an addition of coumon salt, by which means thio silyer is converted into a chloride. 2d. In dissolving the ebloride of silver iu the roasted ore by means of hot concentrated brine and conveying it iu solution to proper vessels for precipitatiou. 3d. In preeipitating the precious metal in the form of cement silver by the ageney of metallic eopper, and in refining the silver so produeed, for the inint. ‘ At Freiberg, in Saxony, where I had an opportunity of studying this method practically, it is employed for extracting silver from a rich copper maite, that is obtained from enpreons silver ores in the course of the peculiar treatiaent knowu as “eommon lead snielting.” The cupola furnaces produce, beside the rich lend, which is sent to the process of cupelling, a sulphide of lead, iron, copper. silver, &e., which is concentrated by repeated fusions until most of the lead has been eollected as rich lead, most nf the iron passed into tho slag, and a sulphide of eopper, iron und silver obtained, whieh in the year 185 contained an nverage of 69 per cent. of the first named metal, and 0.42 per eent. of the last. This matte or regulus is broken into fragments by hand, and pounded to a fine powder beneath aseries of heavy iron stamps. It is now carefully sifted through a brass sieve containing 2500 apertures to the square ineh, and is in a condition to be submittod to tbe process of roasting. ‘The furnaee is of the eommon reverberatory elass, bnt much smaller than those used in Manslield by Ziervogel. ‘The fuel employed is sinne coal, and one attendant is suflicient to carry on the work. Four hundred weight of mineral nre placed on tho hearth at onee, and the fire gradually inereased in strength while the attendant stirs coutinnally, and oceasionally turns the charge eutircly in the furnace, that overy pnrt may be exposed to an intense heat. At the a} of nbout cight luurs the proofs nf complete roasting begin to nppenr; the powder becomes brown and eartliy, the heat does not produee that interior glow which is an evidence of tho presenee of sulphur, nud no fumes ef sulpburous acid are to be perceived. ‘hen the eontents of the fimace are drawn out, allowed to enol. and earried to a mill resembling that usnolly employed for grinding eor:, and after being ground and bolted is brought back to the furnace to be subjected to the ehlorizing rousting. The eopper and iron of the regnlns exist now partly in the form of sulphates, while tho silver is present as a sulphate or in 2 1actallic conditivu. The powder is placed in the same fnrsaee, iu charges of three hundred weight, and roasted for a short time, then mixed witb five per cent. of common salt, and the heat and stirring eontinued for about three hours. During this time the chloride of sodium, or salt, is deeomposed by the sulphuric acid uf the sulphides, ane the free chlorine thus formed combines with the silver, for whieh it has a strong affinity, until, nearly if not quite oll of the valuable metal has taken the form of a chloride. Vhe powder is now drown froin the furnaee and carried in iron trays to the department devoted to lixiviation. ‘This is an elevated room eontaining a number of strongly made, round wooden vessels rauged in a manner siinilar to those at Wettstedt, which have already been described, in rows one above the other, so that the fluid poured in at the upper level will deseend step by step to the bottom. Besides the vessels alarge vat at a still bigher level holds the store of hot brine, which is heated to the proper temperature hy passing steam through it. igbt of the above mentioned tubs occupy the upper row, and in these the dissolving of the ehlorine of silver takes place. The powder, still warin from the furnace, is plaeed in each to the amount of Gewt., and the hot brine allowed

to run in upon it. The fluid passing through the mineral mass comes in contact with the fine partieles of ebloride of silver, tukes this compound into solution and carries it through a filter of linen and straw that forms a false bottom of the tub, and thence by tronghs into two reservoirs, whiere the earthy particles mechanically suspended in tho fluid are allowed to settle. ‘Phe process of lixiviation is continued for each tub of powdered mineral, until a bright copper plate, placed in the steam flowing through tho filter shows no indications of n silver precipitate. The solution of the precious metal is now assunied to be as eomplete as possible for the present, and the contents of the tubs are assayed, that the amount of silver remaining may be determined, and that no loss from unpereeived neeidents in roasting nr dissolving may occur. Wheu more than one thirty-third per cent. remains, the powder is again sent to the furnace, roasted with salt, and subjected to another treatment with brine, as above described. If contaning less than one thirty-third of a per cent., which is generally the case, it is enrried to the appropriate furnaces and fusod fir copper. The argeutiferous brine Howing from the lixiviating tabs, after being allowed to deposit the partieles that may be held in mechanieal suspension, passes into three tubs, each containing a layer of eement eopper eight or ten inches deep. ‘The superior attraction of copper for chlorine causes the silver to he precipitated ina reguline eondition as cement silver, while the former metal is taken into solution in its plaee, and carried forward into a fourth range of tubs, where, in order tbat the coniplcte precipitation of the silver may be secured, the brine is brought the second time into contact with fincly divided copper. A still lower range of tubs receives the fluid which now holds much copper in solution, aud where, by means of inetallic iron, the copper is in its turn precipitatedin the form of cement eopper. 'Vhe fluid passes into other vessels eontaiuing iron, that it may be eompletely freed from its copper, and then flows into a reservoir benenth the floor of the apartment, and is finally ppmped into the reservoir spoken of in the commencement of the description, to be heated and passed again over the argentiferous owder, The silver falling in tho precipitation tubs is collected every eight or ten days, clenred of particles of copper by passing hydrochlorie acid over it and placed in a vat where for a period of twenty or thirty days it is allowed to remain in pure water, which is occasionally renewed. It is thon placod in an iron pan upon the top of the furnaco and allowed to dry, and finally, it is eartied to the refluing department, where it is fused and purified. 227. Not only is the separation of the silver more eoinplete than by the method of liquation formerly in use, but the copper obtained by smelting the lixiViuted remnainders is fond to be nach superior to that obtained by the nnetent method, since daring the complete roasting at the Legiming of the process, & greater part of tho ontimony and arseni¢ arn driven off into the atanosphere. Rock Springs District--Colorado, Mining in the Colorado region is in nowise confined to the eountry adjacent to the river. ‘There is every reason to believe that tho entire eonntry between tlnt river and the eoast, and indefinitely to tho eastward, will be found ricb in mines nf gold, silver andeopper. Wherever prospectors have started in, they appear almost invariably to meet with suecess. The Roek Spring district, abont 50 miles frou El Dorado Canon, on the road theuee to Los Angeles, is already beginning to assume eonsiderablo importance. So extensive have these mines becomo that the miners m that neighborhood have found it neeessary to divide the distriet, and n new one has reeently beeu formed from the northerly portion, and named “ Macedonia District.” Roek Spring Distriet is five miles square, hnvitig Silver Ilill for its eenter, while Macedonia Iiill has been fixed as the center of the district of that name. In the latter, work has been actively commeneed in the Mncedonian lode and the Blus Ophir. ‘The Mammoth Company, in Rock Spriug District, aro pushing ahead vigorously with their tunnel. ‘This is said to present an immense lode at its outcrop, and is likely to he very valuablo. An assay recently mado from what is supposed to be a narrow spur, struck in the tunnel, yielded $540 to the ton. ‘Tbe rock from the croppings has assayed at n iuueh higber figure. This tunnel is being driven through very hard gronite. The shaft of the Pride of the Union was down about 70 feet at tho time our informant passed that way, and tho company were taking out some very fine-looking ore. A contract has heen giveu out for sinking a shaft on the Montezuma lode. The Macedonian cry is heard from these mines, “Come over nnd help us!” ‘There is room euough for all who come with means to locate and develop the miues. Companies in this city who are sending men there with hnolf means, however, nre making a great mistake. Thero are uo placer mines tbero from whieh a temporary support ean he derived; neither are there any mills as yet for crusbing and taking the bullion from the ore. The developments are already sufficient to warrant the putting np of a small prspecting millin this neighborhood, say on the road at the Rock Springs Camp, which would be central. Why do not the companies in this eity interested in these mines unite in an enterprise of this kind? If such a project should bo committed to proper hands it would not only be a paying investment, but demoustrate at once, and at small aggregate cost, the value of tho distriet. A mill put up aud run on this plan will save to the miners the extortionate charges of n speculating company, whnse aim is too often to ruin the reputation of a mining neighlorhood, in order to freezo out the locators and buy up their claims for a song. Assays have already shown that silver exists there in large quantities in “specimens,” and the pick nnd shovel bave proven that the lodes are heavy and continuous. We hope soon to be able to reeord the fact that the maehinery bas left this city for a mill for Rock Springs. ‘There is plenty of wood in the neighborhond for fnel and timbering, and thousands of acres of the best quality of mountain bunch grass. Screntiric Sacrinece.—It is said that the French Commission, under the direction of M. de Saulay, is rifling the tombs of tbe prophets and exhuming tho remains of venerated Israelites, to enrich tho seientific eollections at Paris. Many of our Israclitiah friends are much aggrieved at this sacrilege, and justly urge thnt zeal for science should ucver infringe upj-on subjects justly held sacred. ‘ ®