Show mechanical bechani cal improvements im in in concentration by 0 H JOHNSON this being a time of large milling plants the past year is most notable for the exhaustive hau stive testing and experimental work of the metallurgist to increase recoveries at no time in the history of ore dressing has so great ian an efforts been made to increase e efficiency in concentration as in the past year the low grade of the ores and the big tonnages ton nages being the problems to solve mechanical concentration and flotation methods received the most consideration the progress made may be learned from the developments in fine concentrating equipment sand tables about sixteen years ago the science of ore dressing received its great contribution from A R wilfley in the wilfley concentrating table which was the result of his inventive genius and experience in treating ore at kokomo kokomos colorado it was a radical advance in ore dressing and made possible the treatment of low grade ores hitherto beyond economical treatment since the introduction tro of this machine into c commercial use many changes and improvements have been made in the design still the first machines were so complete in principle that they could not be improved upon without infringing upon the principle of the first table therefore the wilfley table still holds its position as the I 1 leading concentrating cent rating machine for the treating of sand mechanical improvements haave been incorporated corp orated in the wilfley table from time to time as experience has warranted until the no 6 machine with its steel construction was brought out comparing it with the older models in place of a cumbersome timber base a neat strong channel iron construction st has been substituted the steel frame is formed of two 12 inoh inch steel channels 15 feet long spaced 20 inches apart and bolted securely to cast iron separators this type of frame gives greater stability and has made it more readily adapted to either wood or concrete pier foundations the head motion is baited to the top of th the e channel frame and is made up of a broad heavy box section frame cast in one piece with the eccentric shaft supports in these supports is carried an eccentric shaft upon which the pitman is mounted the pitman engages bronze toggles through which the motion is imparted to the deck by means of a yoke A heavy spring held in a cast pocket on the front frant keeps the toggle parts in unison this motion is more substantial than the previous ones and having all wearing parts accurately machined is a perfectly smooth running mechanism engineer with mine smelter supply co salt lake city the tilting device is a material improvement A large single hand wheel with a heavy mitre gear connection operates two tilting rods which are connected to the cast iron yokes carrying the slipper bearings in place of rockers for the table supports slipper bearings running in oil are provided making replacements of these parts far less numerous than have been required on the former model of machines the phenomenal success of tile the wilfley machine and the continued demand for higher extraction lin in the immense mills of the country have encouraged others to enter the field the opportunity to exploit tables and improve designs has been greatly augmented by competitive testing and experimental work carried on in the various reduction works the answer to all this work was the development of several different types of concentrators all of chica have had more or less degree of success it also resulted in wilfley improving head motions frames decks so as to give the maximum efficiency with a minimum amount of upkeep up keep and attention the deister probably the most notable of the later table development is the deister as made by the deister concentrator company fort wayne in 1908 deister first introduced his no 2 sand table and no 3 slime machine and these particular machines have had a wide acceptance and been installed on a large scale especially in the southwest the no 2 has now been superceded superseded super ceded by a no 4 and no 5 type the former of this latest model is recommended for the handling of classified and table feeds up to eighty mesh and for roughing work of eight mesh and finer the deck is long and narrow a sort ot of parallelogram with the motion mounted next to one of the long sides and the feed taken on at one of the short sides the tailings are discharged at the opposite short sides the overall length is eighteen feet nine inches and the extreme width is five feet seven inches the table top is made up of several sloping planes beginning at the feed box there is for a distance of about sixteen inches a smooth surface with a gentle slope which terminates with a depression having gently sloping sides in the bottom of these pools are applied four straight riffles fiffles about one fourth inch wide by one sixteenth inch thick seventy seven inches long these four strips end in a straight line with a smooth surface between them and the concentrate discharge on the very top of the ridge and toward the tailings side is a higher riffle starting next the motion side with a block two inches high eighteen inches long then an one 1 eighth inch riffle running about ten inches beyond the ends of the four riffles fiffles in the pool it is then continued to the concentrate discharge side by a thinner strip terminating mina ting at another block size x there are six groups of riffling and between each is a smooth gently sloping surface about five inches wide the deck is also arranged so that the pools shallow gradually towards the motion side and concentrate cen discharge the surface next to concentrate launder is practically levell level in the line of motion the pools with sloping sides is the particular new feature the no 5 table is suggested for fine sand feeds and is riffled raffled and has the ridges the he same as the no 4 the deck is not so long but is wider the deck covering is linoleum i the james table the james table has enjoyed most of its favor in the cobalt district its being on the market is attributed solely to mr james personal efforts he tests and experiments with each condition and builds a table to suit he makes strong claim to the first rights of the inclined planes on decks the sand table is long and narrow with riffles fiffles in addition to an inc incline linee plane the slimer is wide and long without any riffles fiffles on top of the linoleum there being a few riffles fiffles underneath to make the several pools which are the features of this machine the tables table professor has put upon the market a new sand and slime table this is designed to handle only closely classified feeds constructed in different sizes to suit the ore being treated since concentration is effected by two forces the motion of the table which ad vances by friction the material in contact with the surface and the washing ff of the mater material al across the deck by water carries out the principle by using a narrow long table for coarse heavy mate rial as the stratification is effected more by the motion than the water force whereas 1 with fine material a wide short table suro sur O J face is used as the action of the washing water vater is the more important force the coarse tables are riffled raffled and the fine tables have grooved to suit the feed these tables and Over stroms system of classification have been installed in the mill of the yellow pine M mining c 1 company goodsprings Good springs nevada and in the exper experiment linen j tal section of the st louis smelting smelling Sm elting re K fining company st francois missouri the former type of Over table which was manufactured by the allis chalmers company has recently been taken hy by the delster deister concentrator Coffi company pany over ov the isbell Tini universal versal concentrator has advertised extensively during the past been avear year its claims are that it takes an direct on eight to sixty classified lassi fied fe feed ed U or reg re binding grinding mills and it screen mesh b mineral that will pass mesh or es eg sav I 1 br along with the coarse concentrates the particular feature of this mahine this TS is chine as it is directly opposite to most of the dg arese prese present nt practice which is to classify fy and treat coarse cears e feeds on one table and fines on another the table is long and narrow with the deck supported on six rockers motion is attached to the feed end and the line of reciprocation is lengthwise of the machine the deck is divided by a partition run jiing from the feed to discharge end presenting two working sides each part of the deck is riffled raffled with riffles fiffles converging from the sides to the center in which are located special openings for drawing oy os the concentrate the principle of operation is that with the longitudinal movement the feed is carried towards the discharge end the mineral stratifying along the surface this mineral increasing in depth from the continued feed travels forward along the dobli oblique A ue riffles fiffles crowding the sand over them and toward the outer edge of the table the riffles fiffles are of unequal lengths so the concentrate is advanced to the cutout cut out the mineral which was crowded over with the sand past the first cutout cut out is grated in the next group cf riffles fiffles leading to the several openings and the opp operation ration is repeated the whole length of the table the tailings are discharged from the end along the sides and a middling taken from the center of the end some machines have been installed in arizona and idaho but up to date its adoption has not been very extensive other sand tables which may be mentioned as presenting some change in design are the card franz eccleston roughing tables the roughing system in the large mills of ih the eUtah utah copper developed the garfield table which is made by the mine aline smeller supply company this table is mount with a no 5 wilfley head motion the deck k is is supported on four chilled iron rockers carried on two heavy cast iron tilting bars ars arranged to give a steep pitch the lable babl e top proper is four feet wide by twelve feet long riffled raffled over the whole face with th high riffles fiffles three fourths inch bt at ba back 11 k t tapering to three eighths inch at front aront the feed and water boxes are car tied nad on one side taking up all the space tofiq ae tailings are discharged on the appo ate S ald de and the concentrates taken off the e end there is a permanent slope of an filch aca and a a half in the width of the deck Y mol eunas urns U used seed on these decks are oneth lich inch I 1 thick considerable trouble was countered in getting the riffles fiffles shaped to withstand the coarse heavy feed and Malli tain a corner finally and edge it was solved at s the arthur plant by beveling the top and bottom of riffle to conform to the s permanent slope of deck these tables handle about tons per twenty four hours son they y are used for a rough separation of th the concentrate from the sand no finish product is made the tailings are reclassified reclaimed the coarse going to re grinding machines the fines to further classifiers and boughers rou ghers the concentrates are retreated on wilfley tables the roughing system has been installed at the butte superior at butte montana and in order to accommodate the ln increased lucrease crease tonnage in the original mill space these boughers rou ghers were built with two working decks one set directly over the other the feed is divided by a distributor on the machine the double deck machines work equally as well as the single deck and possess the valuable feature of saving room wilfley placer machine based on the roughing table principle a further extension in the use of concentrating tables has been found in placer work for this purpose a wilfley roughing table was designed it is essentially the same las the no 6 standard wilfley with an alteration in the deck riffling making it possible to treat from five to ten tons of material per hour eliminating 80 per cent waste and delivering a concentrate product which is retreated on a finishing table by this method two tables handle a large tonnage at a low cost which is so necessary to make placer work commercial besides it catches all the gold which does not readily amalgamate and is usually lost in the ordinary methods of placer mining FX extended tended operations of the concentrator is looked for in the near future among placer miners wilfley rougher the wilfley rougher is also becoming I 1 extensively used in regular concentration it has the advantage of making a finished product this machine was thoroughly tried out in the test plant of the inspiration copper company and proved a big success recovering a little better than GO 60 per cent of the entire mineral value of the ore and made a clean concen concentrate running from 38 to 40 per cent the timber butte milling company is installing eight of these tables in its new zinc concentrator slime machines following the well accepted slime machines such as the isbell va vanner and the standard delster deister no 3 we have the revival reviva of a huddle buddle and canvas table made produced with new along new designs and novelties these types are exemplified by the wilfley mul the P porter orter the deister tipping an and d the anaconda round table the aim of the designer has been surface with small to make use of large mill space Exien extensive sive testing and experimental work has been carried on in ill the development of these machines long try f outs were made at miami utah copper anaconda copper and ohio copper the usual mechanical difficulties which attend the introduction n of new apparatus developed in these tests but the engineers are successfully overcoming the problem deister tilting ahmer S limer the delster deister tilting machine has six decks 10 feet wide by 12 feet long covered with oiled and painted canvas having a fine sand dash treatment when paint is wet the decks are pivoted between two cpr upright i standards being automatically tilted forward when the feed is flowing and back when washing off the concentrate the feed is taken on for a predetermined period usually ten minutes when the reversal of inclination takes place which closes off the feed and opens the valves admitting the wash water there is no shake to the machine and it can be tilted mechanically or with air this type is made by the delster deister machine company several have been installed in the miami plant the porter slimer the porter is a non movable machine made by the deister concentrator company it has twelve decks each 12 feet long and 10 feet wide the decks are covered with cement each dach deck has a distributor the wash water is supplied from a header running along the top side of the machine which supplies four manifolds from each manifold are twelve spray pipes extending across the decks by means of a timing device and valves the water is first ad to one manifold which washes one section then the next manifold is opened washing another section and so on to the end the decks are adjusted for slope from the discharge box wilfley multi deck the wilfley multi deck is the latest ef fort of mr wilfley it is different from the previous climers in that it is a reciprocating machine and having two groups of decks the flow of feed need not be shut off they are made with three or six or twelve decks on a side the feed box is supported on top and so designed as to give a thorough distribution to all decks first on one side and then the other the decks are covered with grooved for description and cycle of operation see the mining review of november 30 1913 A great deal of testing was done with this machine at inspiration and miami I here a 50 50 per cent saving sa ving was made yielding a concentrate of 37 per cent the silver |