MILLIONS SAVED BY FROTH
WORTHLESS METAL MINES
suddenly become productive—worn-out ore-heaps are now valued at millions; in short, a revolution in the zinc, copper, and lead industries, all wrought by froth.
Some journalistic romancers will have it that the wondrous powers of froth were discovered by a washerwoman with her suds; but Gail Martin brands this as a fiction. Writing in The Compressed Air Magazine (New York) on "Wonders Worked by Selective Flotation," Mr. Martin describes what he calls "the metallurgical miracle that has turned losses into profits." He says:
"Froth is raising millions of tons of mineral each year to a state of high commercial value. Through the alchemy of science, an oily, fluffy, dirty-gray froth is separating complex sulfid minerals and segregating their component parts—zinc, lead, copper, silver, and iron—into valuable products. Difficult smelting problems have been overcome; waste has been converted into profitable ore; and all through the discovery that froth can be made to accomplish what no other known mechanical or chemical agency will do as economically or effectively.
"Of what avail would efficient mining be without economical methods of converting ore into metal? In the last analysis the prosperity of the non-ferrous metal industry rests upon a substance as unsubstantial as froth.
"Five years ago it was realized that the high-grade, desirable smelting ores had been nearly exhausted. Available reserves consisted of low-grade complex ores containing heavy percentages of zinc. As depth was attained, the zinc content increased. This was particularly true of the Rocky Mountain region.
"Now in lead smelting, the presence of zinc in an ore formerly increased the cost of recovering the lead; and the zinc, then being irrecoverable, was lost in the slag. A ban was placed on lead-zinc ores; vast tonnages could not be mined; and large mines lay idle, while scores of others faced a shutdown. Three years ago, metallurgical plants in Salt Lake Valley, Utah, poured on their slag dumps daily approximately 100,000 pounds of zinc valued at about $6,000, or $2,000,000 worth annually. Today, the greater part of this metal is saved, with the result that from Utah ores alone the output of zinc in the Beehive State increased from 8,157,739 pounds in 1920 to 16,000.000 pounds in 1924, and from 52,611,732 pounds in 1925 to 100,000,000 pounds during 1926.
"Nearly every one has performed the experiment of filling a glass of water until the surface of the liquid stands higher than the sides of the vessel; or of greasing a needle and placing it on water where it will float. In a similar manner, it was found that sulfid-ore particles, when oiled, have a tendency to attach themselves to air bubbles and to float, while the oxid particles—such as quartz, feldspar, limestone, hematite and other gangue minerals, which have less affinity for oil and are therefore easily wetted—sink to the bottom or remain in suspension. Here one meets the first paradox—the heavier particles float while the lighter ones sink. In fact, some of the heaviest sulfid minerals are easiest to float, provided of course they are ground fine enough so that the weight of the mineral particles will not counteract the weight of the bubble.
"Flotation, like many other innovations, had a modest beginning and a comparatively slow development. While no one knows just where the idea originated, the first patent that bears a resemblance to present-day practises was taken out by William Haynes in 1860.
"An article on flotation would be no article at all unless it mentioned Mrs. Carrie Everson. This woman—in a story broadcast by an ambitious but none-too-accurate newspaper scribe and swallowed whole by a gullible and romance-loving public—was painted as a hard-working Cripple Creek washer-woman who beat scientists to fame and fortune by discovering, while washing a miner's ore-plastered overalls, that the froth made by soapsuds and rubbing would float mineral sulfids, and that valuable recoveries could thus be effected.
"Mrs. Everson was not a washerwoman. She was the wife of Dr. W. K. Everson, and had acquired a considerable knowledge of mining and chemistry. Through her husband's mining investments, Mrs. Everson became interested in mineralogy, and patented the Everson flotation process. Altho nothing of practical benefit resulted from her enterprise, Mrs. Everson did discover that the addition of a small quantity of acid to the pulp or crusht ore increased the selective action of the oil in the case of sulfids, and that agitation further aided the separation of the desirable mineral particles.
"Various other inventors contributed liberally to flotation; but the first long stride toward the practical application of this method of ore dressing was made in 1904, when Francis Ellmore invented the first workable flotation process; altho to Potter, Delprat, and Froment must go the credit for the discovery that oil particles can be raised by air or gas bubbles adhering to mineral sulfids. These pioneers paved the way that led to the recognition of the fact that the key to flotation was neither the oil nor the apparatus, but, instead, the air bubbles."
After the recognition of this principle, the evolution of selective flotation was rapid; and, today, this method of ore dressing is declared to be the foremost metallurgical discovery of the age. According to a bulletin on "The Trend of Flotation," by Arthur J. Weinig and Irving A. Palmer of the Colorado School of Mines, "No other method of ore treatment has ever effected such great changes in so short a time. This is indicated by the number and importance of the companies now using the process, the tonnage and variety of ores handled, the grade of concentrates produced, and the high recoveries of the metals contained in the ores." Mr. Martin goes on:
"Utah, the second largest lead producer in the United States, yielded during 1926 in round numbers 300,000,000 pounds of the gray metal. More than half of this came from ores which, if treated by old methods would not have covered treatment costs. In addition, from 90,000,000 to 100,000,000 pounds of zinc would have been burned up in that twelvemonth in recovering that amount of lead.
"The Sullivan Mine near Kimberley, British Columbia, about a decade ago, was purchased for $250,000. During 1925 alone the net earnings were $13,255,406. The Combined Metals Mine at Pioche, Nevada, lay unproductive for years. To-day from 150 to 200 tons daily are being shipped to the notation plant. Mines that have been the beneficiaries of notation could be enumerated to the point of boredom. To-day, copper-mines are operating at a profit in the face of low prices for the red metal largely because of the efficacy of flotation. Were it not for flotation, low-grade ores could not be treated successfully, profits would be wiped out or reduced to a pitiable figure, and a great industry would be rendered helpless.
"It is comprest air and agitation that form the froth which becomes dotted with mineral and bears off the desired particles.
"The accomplishments of selective flotation are positively uncanny. Even in vast mills like that of the Utah Copper, with a combined capacity of from 45,000 to 50,000 tons daily, a saving of copper ranging from 90 to 95 per cent. is made in the case of ore carrying but 1.1 per cent. copper or twenty-two pounds of the red metal to the ton, as compared with recoveries averaging around 60 per cent. when milling was first started by the company hardly fifteen years ago."
Source: The Literary Digest for July 2, 1927
Some journalistic romancers will have it that the wondrous powers of froth were discovered by a washerwoman with her suds; but Gail Martin brands this as a fiction. Writing in The Compressed Air Magazine (New York) on "Wonders Worked by Selective Flotation," Mr. Martin describes what he calls "the metallurgical miracle that has turned losses into profits." He says:
"Froth is raising millions of tons of mineral each year to a state of high commercial value. Through the alchemy of science, an oily, fluffy, dirty-gray froth is separating complex sulfid minerals and segregating their component parts—zinc, lead, copper, silver, and iron—into valuable products. Difficult smelting problems have been overcome; waste has been converted into profitable ore; and all through the discovery that froth can be made to accomplish what no other known mechanical or chemical agency will do as economically or effectively.
"Of what avail would efficient mining be without economical methods of converting ore into metal? In the last analysis the prosperity of the non-ferrous metal industry rests upon a substance as unsubstantial as froth.
"Five years ago it was realized that the high-grade, desirable smelting ores had been nearly exhausted. Available reserves consisted of low-grade complex ores containing heavy percentages of zinc. As depth was attained, the zinc content increased. This was particularly true of the Rocky Mountain region.
"Now in lead smelting, the presence of zinc in an ore formerly increased the cost of recovering the lead; and the zinc, then being irrecoverable, was lost in the slag. A ban was placed on lead-zinc ores; vast tonnages could not be mined; and large mines lay idle, while scores of others faced a shutdown. Three years ago, metallurgical plants in Salt Lake Valley, Utah, poured on their slag dumps daily approximately 100,000 pounds of zinc valued at about $6,000, or $2,000,000 worth annually. Today, the greater part of this metal is saved, with the result that from Utah ores alone the output of zinc in the Beehive State increased from 8,157,739 pounds in 1920 to 16,000.000 pounds in 1924, and from 52,611,732 pounds in 1925 to 100,000,000 pounds during 1926.
"Nearly every one has performed the experiment of filling a glass of water until the surface of the liquid stands higher than the sides of the vessel; or of greasing a needle and placing it on water where it will float. In a similar manner, it was found that sulfid-ore particles, when oiled, have a tendency to attach themselves to air bubbles and to float, while the oxid particles—such as quartz, feldspar, limestone, hematite and other gangue minerals, which have less affinity for oil and are therefore easily wetted—sink to the bottom or remain in suspension. Here one meets the first paradox—the heavier particles float while the lighter ones sink. In fact, some of the heaviest sulfid minerals are easiest to float, provided of course they are ground fine enough so that the weight of the mineral particles will not counteract the weight of the bubble.
"Flotation, like many other innovations, had a modest beginning and a comparatively slow development. While no one knows just where the idea originated, the first patent that bears a resemblance to present-day practises was taken out by William Haynes in 1860.
"An article on flotation would be no article at all unless it mentioned Mrs. Carrie Everson. This woman—in a story broadcast by an ambitious but none-too-accurate newspaper scribe and swallowed whole by a gullible and romance-loving public—was painted as a hard-working Cripple Creek washer-woman who beat scientists to fame and fortune by discovering, while washing a miner's ore-plastered overalls, that the froth made by soapsuds and rubbing would float mineral sulfids, and that valuable recoveries could thus be effected.
"Mrs. Everson was not a washerwoman. She was the wife of Dr. W. K. Everson, and had acquired a considerable knowledge of mining and chemistry. Through her husband's mining investments, Mrs. Everson became interested in mineralogy, and patented the Everson flotation process. Altho nothing of practical benefit resulted from her enterprise, Mrs. Everson did discover that the addition of a small quantity of acid to the pulp or crusht ore increased the selective action of the oil in the case of sulfids, and that agitation further aided the separation of the desirable mineral particles.
"Various other inventors contributed liberally to flotation; but the first long stride toward the practical application of this method of ore dressing was made in 1904, when Francis Ellmore invented the first workable flotation process; altho to Potter, Delprat, and Froment must go the credit for the discovery that oil particles can be raised by air or gas bubbles adhering to mineral sulfids. These pioneers paved the way that led to the recognition of the fact that the key to flotation was neither the oil nor the apparatus, but, instead, the air bubbles."
After the recognition of this principle, the evolution of selective flotation was rapid; and, today, this method of ore dressing is declared to be the foremost metallurgical discovery of the age. According to a bulletin on "The Trend of Flotation," by Arthur J. Weinig and Irving A. Palmer of the Colorado School of Mines, "No other method of ore treatment has ever effected such great changes in so short a time. This is indicated by the number and importance of the companies now using the process, the tonnage and variety of ores handled, the grade of concentrates produced, and the high recoveries of the metals contained in the ores." Mr. Martin goes on:
"Utah, the second largest lead producer in the United States, yielded during 1926 in round numbers 300,000,000 pounds of the gray metal. More than half of this came from ores which, if treated by old methods would not have covered treatment costs. In addition, from 90,000,000 to 100,000,000 pounds of zinc would have been burned up in that twelvemonth in recovering that amount of lead.
"The Sullivan Mine near Kimberley, British Columbia, about a decade ago, was purchased for $250,000. During 1925 alone the net earnings were $13,255,406. The Combined Metals Mine at Pioche, Nevada, lay unproductive for years. To-day from 150 to 200 tons daily are being shipped to the notation plant. Mines that have been the beneficiaries of notation could be enumerated to the point of boredom. To-day, copper-mines are operating at a profit in the face of low prices for the red metal largely because of the efficacy of flotation. Were it not for flotation, low-grade ores could not be treated successfully, profits would be wiped out or reduced to a pitiable figure, and a great industry would be rendered helpless.
"It is comprest air and agitation that form the froth which becomes dotted with mineral and bears off the desired particles.
"The accomplishments of selective flotation are positively uncanny. Even in vast mills like that of the Utah Copper, with a combined capacity of from 45,000 to 50,000 tons daily, a saving of copper ranging from 90 to 95 per cent. is made in the case of ore carrying but 1.1 per cent. copper or twenty-two pounds of the red metal to the ton, as compared with recoveries averaging around 60 per cent. when milling was first started by the company hardly fifteen years ago."
Source: The Literary Digest for July 2, 1927