being the lightest, floated on the surface and cooled quickest, it was scraped off and thrown away; the copper, on cooling, readily separating from the regulus which was allowed to cool above it. The latter was remelted and the former was ready for market. The fuel used at these works was pine wood charcoal, costing about thirty-seven cents per bushel. Other smelting works, of a novel and very economical and useful character, have been erected on the La Victoire mine, at Hunter's valley, Mariposa county; at the Buchanan mine, in Merced county; at the Campo Seco mine, in Calaveras county, and at several other mines in various portions of the coast, on a plan introduced by Mr. Nathaniel Haskell, a California mechanic, and called by him the "water-lined cupola furnace." These furnaces are capable of reducing twenty tons of oxides, carbonates, or silicates to good regulus in twenty-four hours. The peculiar feature of this useful invention is a "water lining," which may be described by stating that the cupola consists of two parts, one within the other, like the divisions of an onion. These parts are formed of stout iron boiler plates, strongly riveted at the joints. Between the two there is a space of about six inches; this is kept constantly filled with cool water, by means of a tank above. This cool water saves an immense quantity of heat that would otherwise be lost by radiation, and, as a matter of course, affects a corresponding saving in fuel. No fire bricks are used in these furnaces, which, besides being a great saving in the consumption of this costly article, affects an additional saving by requiring no time, labor, or heat to be lost in replacing these bricks every few days, as they become destroyed by the heat. A very powerful and even blast is kept up in these furnaces by a large cylinder bellows, set in motion by a small steam-engine. One of these furnaces, used at the Buchanan mine, has produced upwards of 100 tons of good marketable copper during the past year, which has sold at San Francisco for from $300 to $320 per ton of 2,000 pounds. That at the La Victoire mine, has only recently been put into operation, but is producing 80 per cent. of regulus at the rate of 24 tons per week. It may be quite proper to state that these furnaces are not adapted to operate on ores containing a very large proportion of sulphur, unless they have been thoroughly calcined, and are combined with a large proportion of other ores or suitable flux. The sulphur has a very damaging effect on the iron of the cupola when both are heated to the necessary temperature to melt the ore. These furnaces will be of great benefit to the owners of mines containing large bodies of oxides, silicates, and carbonates, which are of too poor a quality to ship to market in bulk. They are very cheap and portable, the cupola, blast, engine, and boiler only costing about $3,000, and all combined only weighing about five tons. In 1862 a lady, a Mrs. Hall, invented a novel description of furnace for smelting copper ores, by means of jets of superheated steam being passed into the cupola during the time the fuel and ore were in an incandescent state. To the cupola of this furnace was attached an apparatus for condensing the fumes, previous to their passage into the chimney. This invention was very much lauded at the time by Colonel Charles Harazthy, in a letter published over his own name in the papers at San Francisco. The concentrating works erected by the proprietors of the Keystone mine at Copperopolis are on the principle adopted by some of the large copper mining establishments in Cornwall, England. The ores in these works are operated upon by water. The object sought to be obtained is the separation of the gangue rock by means of the difference in the specific gravity and hardness in it and the ores. There are conditions in which this process is quite simple, cheap, and effective. It is so where the ore is contained in a silicious gangue, or in hard spar, in a locality where there is an abundant supply of free water, constantly running, and where there are plenty of cheap laborers to be had who understand the details of the operations. But as none of these conditions exist at Copperopolis, the experiment, which cost about $50,000, if not an absolute loss, has been only so far successful as only to be of use, at a very heavy expense, during a few months in the winter, when the rains fill the company's reservoirs. And then, in consequence of the ore being free from gangue rock, and the containing slate, from which it is sought to separate it, being of nearly the same specific gravity and hardness, it is not possible to save more than three-fourths of it, at a cost of more than it is worth. These works have been erected in the best manner and of the best materials, under the directions of Mr. Pawning and his brother, two thorough, practical machinists. In the operation of these works the ore is brought between two heavy iron rollers, where it is crushed as fine as possible, and afterwards led, by means of an endless belt, on to five "jiggers," or shaking tables, which are each contained in a large tank of water. The motion of these tables causes all the lighter particles to float off in the stream of water passing through the tanks. These fine particles are collected in "settlers," dried and saved. The coarser grains which do not float off are retained in sieves arranged beneath the tables, and are returned to the rollers to be reduced to the proper fineness. The machinery of this cumbrous contrivance is set in motion by a sixty-five horsepower steam engine. Many other companies concentrate their ores, to a slight extent, by the process described in the description of the Napoleon mine, given in another portion of this report, with such modifications as the judgment of the parties carrying on the work may suggest, or the necessities of the case may compel. The above will probably not be considered a flattering account of the various processes that have been introduced for concentrating and smelting the copper ores found on this coast. But the many failures therein recorded are not of a character to discourage so energetic a people as those of the Pacific coast. The want of success is in so many instances so clearly traceable to the want of skill and experience on the part of the operators that it is evident a plan for profitably working the lowest of these ores will be devised when experience shall have taught those engaged in the business the defects and advantages of the various processes now in use. The few observations contained in this division of the report should be sufficient to convince any reasonable person that the manufacture of refined copper on this coast, with profit, is an impossibility under the present state of affairs. In reviewing the above remarks on these processes, it will be observed that the furnace erected at Antioch was erected as much to test the coal as to smelt the ore. It was made of only sufficient capacity to operate upon eight tons of ore in twenty-four hours. This was a serious error and a material source of loss. The furnace should have been made of a capacity sufficient to have operated upon at least ten tons. Twelve or fourteen tons would have been better, as it requires nearly the same quantity of fuel and the same amount of labor to operate upon eight tons of ore as it would to operate on ten or twelve tons. The furnaces at the copper mines in Chili, which are built on the same general plan, and operate upon ores very similar to those found on this coast, and use a fuel very much like that used here, are constructed of a capacity to work from twelve to fourteen tons of ore in the twenty-four hours. The Chilian copper smelters have no better indigenous coal than is to be found on this coast. They are compelled to import the greater portion of the coal used in their works from England. As good an article, and at as low a price, may be obtained here from Sydney, if it is absolutely necessary to import any coal at all. In California, in consequence of the absence of readily available quantities of oxides, carbonates, and silicate ores, and the preponderance of ores contain ing a large percentage of sulphur, smelting will always be more expensive than it is where a different class of ores are used, because it is necessary to put such sulphur ores through the preliminary process of roasting, which is costly, slow, and sometimes causes much loss. The object of this process is to expel the sulphur, arsenic, antimony, phosphorus, or other deleterious element that the ore may contain, and to oxidize the iron as much as possible. But if this process be carried too far, or the ore contains a very large proportion of the sulphuret of iron, or when the heat becomes excessive, a fusion takes place, which makes the separation of the metal from the sulphur much more difficult. This action in the roasting process caused the loss of many thousands of dollars to the proprietors of the Union mine, by requiring the regulus produced at their smelting works to be roasted three or four times to expel the fused sulphur from it. With Sydney coal, which may be landed at San Francisco at $9 per ton, the reduction of low grade ores to 50 per cent. regulus could be made a very profitable investment for capital. The necessary works, if erected on sufficient scale to afford a market for, say, 8 per cent. ores, would give an immense impetus to the development of the copper resources of the Pacific coast; because, without some such market, all the ores of that standard will be valueless for many years to come, and they form about seven-eighths of all the ores on this coast. To prove that such works would yield a large profit on the capital invested, the following calculation is here given: Costs attending the conversion of ten tons of 10 per cent. ore into 45 per cent. regulus: Ten tons of ore, at $16 per ton. $160 00 10 00 54 00 15 00 10 00 249 00 Ten tons of the above ore produced two and three-quarter tons of regulus of 45 per cent. This is worth $4 per unit, or Deduct freight and expenses attending export.. $495 00 100 00 395 00 249 00 146 00 This profit would be fully 20 per cent. larger if one thousand tons of ore were operated upon. The Bristol copper mine, in Connecticut, when under the management of Mr. H. H. Sheldon, the present superintendent of the Keystone mine, at Copperopolis, paid a very large revenue to its proprietor from ores that did not exceed 3 per cent. in value, on an average. Such a person, after a reasonable amount of experience on this coast, will certainly be able to devise a plan by which ores of three times that value may be worked to a profit. Among the principal causes of the failure of the smelting works tried on this coast have been 1st. The uniform character of the ores operated on. 2d. The want of experienced and steady, skilled laborers. 3d. The misconstruction of the furnaces. At Swansea the smelters have the advantage of purchasing ores of all or any classes, as all are brought there from many different districts. With this assortment of ores at their command, they can arrange the charges of their furnaces to suit their fuel. On this coast there are no established means for obtaining such a wide selection of ores as will admit of their being combined so as to be worked with advantage. Most of the smelting works which have been tried on this coast operate on the ores from generally the one mine on which they were erected, and these are generally of one class. The furnaces built on this coast have generally been copies of such as are used in England, Germany, or France, where fuel of a totally different character is used. The impatience of the parties interested in such works to obtain from them immediate profitable results has prevented the necessary experiments. being made to adapt these imported furnaces to our local fuel. No smelting works have been carried on long enough on this coast to discipline a sufficient number of workmen to conduct the details of the operations with the care necessary to insure success. The few good workmen who have come here from England, France, or Germany, all aspire to be superintendents, or to own a mine themselves, without possessing the ability to impart their knowledge to the more intelligent laborers placed under their direction. All these obstacles to success would be in a great measure removed if extensive works were to be erected at some convenient central point, where those having ores to dispose of could always find a fair market. Such works, properly conducted, would yield a liberal return on the money invested in their erection, and would be of incalculable benefit to the copper interests of the Pacific coast. The export of copper ores from the Pacific coast. It is difficult to obtain a correct return of all the copper ores exported from this coast, as the custom-house authorities have not kept anything more than an approximating account of such as have been shipped through that department; the manifests of the vessels in which it has been shipped in many cases not specifying the quantity of ore taken, only giving its value; in some cases entering it as so many packages of unspecified merchandise of a stated value. This makes it difficult to estimate the quantity, because at the commencement of this exportation the ore was shipped in barrels, casks, and boxes, some of which contained nearly half a ton each, and as the value of the ore differs so much, the value given, if correct, would furnish no basis for calculating the quantity. It is through this cause that the published reports of the exports of ore given in the leading commercial papers of San Francisco at stated intervals differ so much with one another. The reports of the exports for the nine months of the present year, published in these papers, are as follows: The Alta, 15,174 tons; the Bulletin, 15,3503 tons; the Commercial Gazette, 20,848 tons. There is considerable discrepancy in these reports, the Gazette being probably nearest correct. The following list, compiled from every available source, gives the names of mines which are known to have sent ore to San Francisco, and the quantity purchased from each. There are several firms in that city which purchase or make advances on copper ores. Among those most extensively engaged in this business are Meader, Lalor & Co., Martin & Greenman, Mr. Price, Conroy & O'Conner. None of these parties appear disposed to give information relating to their business, under the impression, perhaps, that such information might in some way or other injure them, and it was not through them directly that this list was made out: A total of 78,239 tons, not including any shipments from the Queen of Bronze, or any of the mines in Oregon or Lower California, or any of the many small lots that were shipped as experiments by the mines worked in all parts of California during the excitement about copper that prevailed during the years 1860, 1861, 1862, and 1863. It is quite within limits to estimate the ores received from all unnamed sources since 1860 at 1,761 tons. This, added to the quantities given in the list above, makes a total of 80,000 tons received at San Francisco and exported since the discovery of the mines at Copperopolis. The following table, giving the exports of copper ores from San Francisco from January, 1860, to October, 1866, compiled from the records at the customhouse and the shipping lists, shows a difference of upwards of 22,000 tons when compared with the list above. This discrepancy can only be explained on the grounds above stated. The books of the principal mines given in this list show that the quantities set opposite their respective names have been actually shipped from them. The ores shipped from the leading mines is calculated according to English weight, 2,376 pounds to the ton. Some of the smaller companies may have estimated their ore by the United States weight, or only 2,000 pounds to the ton; but this would not account for so large a discrepancy. |
