OCR Text |
Show SYSTEMATIC PRKPAftATIOS OF JUINIRLIZKD OtLES BY DRY CRUSHING AND COflCESTRA-TlON. COflCESTRA-TlON. VII. Kustel's work od concentration, pub-: lisbed in 1S6S, was written for the American miner and intended to supply sup-ply him with tho condensed results of European progress in this direction, employing water as the medium. What ever statements this author has made relative to the percentage of loss id concentration by water, can therefore be relied upon as not unfavorable to the system advocated, and may be quoted as a standard for comparison. He says : "In the ooocentration of lead ores, galena principally, conducted on the best principles with all the improvements improve-ments of modern concentration in Europe, where great attention and plenty of tirue are devoted totheopera-tion, totheopera-tion, the loss is generally from 15 to 20 ' per cent saviog 80 per cent, of lead ores in concentration may be considered a very satisfactory result-" With regard to the silver ores ho continues: "It must be borno in mind, moreover, more-over, that galena occurs in cubes, the oleavage ia also cubic, very Beldom fibrous, the specifio gravity is 7-5 most favorable conditions for concentration concen-tration while the specifio gravity of the principal silver ores ranges from 5-2 to 6-2 and they have the disadvantage disadvant-age of assuming mostly a fibrous or leaf-like shape when pulverized. The silver sulphuret is heavier (7) but ductile. duc-tile. It is, therefore, quite proper to caloulate on a loss of 35 to 45 per cent, in treating silver ores, provided the plan for concentration is the proper one." "With the concentration of gold the case is difforeot; for its speoifio gravity allows a more perfect concentration, but although under the most favorable oircuin stances from 90 to 95 per cent, of the gold may be saved, there are also cases whore 30 per cent and more might be lost; for instance, if the gold should occur in a very fine scaly condition condi-tion in a clayey rook." Rittinger states the average loss at large of poor argentiferous ores in concentration con-centration by water, as follows : With slimes 60 to 70 per cent With coarse sand 40 per cent. With middle fine sand 35 per cent The best concentrating establishment establish-ment on the Pacific coast, in Nevada, gives the following sample report of work done in silver ores : Value of ore before concentrating con-centrating $69. 83 per ton After passing machine.. 43.22 After passing over eigbty feet of blanket. (Tailings) (Tail-ings) 25.44 " Headings 101020 " A loss of 36J per cent, of silver. In the practice of puddling, as followed fol-lowed in Colorado, the loss of gold and silver carried off by" the water ranges between forty Bnd sixty per cent At Moro V etho, brazil, a loss of gold is sustained equal to ten per cent after a close amalgamation followed by a concentration of the impoverished impover-ished sulphurots, conducted wiib Tory great care over a great length of strakes. These ores are worth about $S per ton, and not heavily sulphuretted. sulphuret-ted. Assuming that we have, in the above brief statement, a fair representation of what is accomplished by the water dressing of galena, silver BulphuretB and gold ores, we will now oondense some figured statements of results obtained ob-tained by dry concentration, an like ores, in small and in large quantities, but without the employment of a sizing siz-ing apparatus. 1. ) Statement of J. T. Lewis & Bro., Philadelphia. Sample Galena (Sulphide of lead) content 5.80 per cent Blende (Sulphide of zinc) content con-tent 23.28 " " Gangue, carbonate of lime, heavy spar. Tailings Galena 0.S7 per cent " Blende 2.75 " " Loss in Galena about 15 per cent., in Blende about 11 per cent. 2. ) Sbeba Ore, Silver, Nevada. Sample 43 lbs. Value per ton $244.29 . S lbs. headings. Value per ton $1236.11 Tailings. Value per ton 826.09 Loss in tailings not quite 1 1 per cent. 3. ) De Soto ore. Silver, Nevada. Sample 38 lbs. Value per ton $153.61 4 lbs. headings. Value per ton $1316.27 Tailings. Aralue per ton $19.14 Lost in taiUnqs not Quite 13 per cent. 4. ) Mammoth Galena lode, Nevada. Sample 48 lbs. Value por ton. .$172.55 174 lbs. headings. Value per ton $469.36 Tailings. Value per ton $34.78 Loss in tailings a fraction over 12 per cent. 5. ) Lexington mill tailings, Colora do. Sample 30 lbs. Value per ton, gold $6.20 Value per ton, silver.... $4 Sl 9 7-10 lbs. headings. Value per ton, gold .25.83 Value per ton, silver 10.85 Tailings, value per ton, gold,.. trace " " silver 1.76 Loss in silver a fraction 6vcr 36 per cent. 6. ) Bates mill ore, Colorado. Sample 100 lbs., value per too, gold $20.67 Value per ton, silver $744 40 lbs., headings Tailings, gold 2 58 " 6ilver 2.65 Loss in go7d 12 per cent., tilvcr 35 7-10 7 Various lots of Colorado mixed oro separated by a full-sized working machine, without siziDg tho ore. Sample 23,000 lbs., value per ton $27.00 Headings per ton ... . $85.00 Tailings 7,25 " 3025 lbs,, value per ton 35.20 Headings per ton.... S3. 43 Tailings 13.72 ' 5600 lbs., value per ton 25.37 Headings per ton 98 93 Tailings 10.99 " 5540 lbs., value per ton 12.54 Headings per ton.... 99 59 Tailings 3.62 " 6651 lbs., value per ton 46.66 Headings per too 162.48 Tailings 9.05 " 6210 lbs., value per too IS, SO Headings per ton. ... 11013 Tailines 4,27 Quantity 50.026 lbs., or 25 tons average value of ore per ton, $27.60; average of headings, $106.41; of tailings, tail-ings, $8.15. Ihcro beintr no means for sizing the ore upon which these experiments were made; a second running of the tailings was undertaken in order to show the effect of preparing the ore properly. Tailinrs assaying 513.72 Kavo tailings worth only '. Tailing as-aying $10.S9 gave tailings worth Tailings afsnying $vl.lJ gave tailing worth only Tailing assaying $1.27 garo tailing! worth only 5J.i.'. Tallinn assaying &-0ogaro tailinsB worth Tailines averaging $8.33 per ton I were reduced to $2 47 per ton. It if interesting to notice the uniformity of amount left in the tailings regardless of the original value. Whilst this is the case with orus of a low grade, it will be observed that in rich ores the amount in value left in the tailings will be increased (without greatly i changing the percentage on the original origi-nal value of the ore), in other words, after the fixed minimum of loss there will bo an almurt rugi.l ir incrtaseof uietalic partiule.-i alo left in proportion propor-tion to the richness of the mineral. The Washington mill, Georgetown, Colorado, treated 423 cons of silver ore by dry crushing and concentrating, without siing. Original ere when dried, 407 tons; headings 178 tons; tailings 229 tons; value per ton of ore $54 22 ; of tailings $3.91 ; loss about $4 OS per cent More examjiics might be given and many comments might be made on those presented, but here are sufficient to excite the interest of the intelligent reader and put the practical operator on the alert to obtain direct and personal per-sonal information on a subject so important. im-portant. Examples could also be given giv-en concerning the efficiency of the machine ma-chine in separating injurious substances substanc-es from minerals where the use of water wa-ter fails entirely, such as iu kryolite containing spathic iron, tulphide of lead and copper interspersed. The object ob-ject of these articles is attained, however, how-ever, by giving expression to tho writer's writ-er's convictions of tho great necessity for the introduction of a ready and practicable means of separation, accompanied ac-companied with the proofs, many furnished fur-nished under his own direction, which demonstrate to his satisfaction that in this machine the publio gain what is desired. In this interest alone have these several articles been prepared, the writer desiring to aid in furthering the adoption of a systematic treatment of ores whereby mining may not be left to the bap-hazard of inappropriate methods. The breadth of mineral discovery dis-covery in the Sierras of the West is now sufficient to make an industry of over-shadowing importance in thii near future, and probably not a fifth of the mineral wealth of that region has yet been located. The haste for thrift so peculiar to tho American character, has hitherto received a severe set back in the direction of mining as an industry, indus-try, and the wrongs done have been unjustly un-justly charged to the mines. Progress is proving this to be erroneous and tbore is now wanted only a judicious selection from the means placed at the disposal of intelligent operators to make of mining a business as stable and reliable as that of manufacturing, if attended to wiih the same mind for skill and economy. G. W. Bakes. |