US1719442A - Process of ore dredging - Google Patents

Description

' July 2, 1929. J. F. NEWSOM I PROCESS OF ORE DREDGING Filed June 20, 1923 3 Sheets-Sheet l rM lw PM n w W1 Ad .HH OH a q a $3 N m w W H N f ml a wfi 3 8 July 2, 1929, J. F. NEWSOM Filed June 20, 1925 PROCESS OF ORE DREDGING 5 Sheets-Sheet 2 4 lull I I I Inuemoz: JOHN F. NEH/5.0M

July 2, 1929.

J. F. NEWSOM raocnss OF ORE nnaneme Filed June 20, 1928 s Sheets-Sheet JOHN F. A/[WJOM Patented July 2, 1929.

UNITED STATES PATENT OFF JOHN FLESHEB NEWSOM, OF PALO ALTO, CALIFORNIA; JOHN BRANNER NEWSO EXEOUTOR OF SAID JOHN FLESHER NEWSOM, DECEASED.

PROCESS OF ORE DREDGING.

Application filed June 20, 1923, Serial No.- 646,699, and'in the Federated Malay States February 7, I923.

Owing to the low value of the material handled by ore dredges, it is imperative to handle very large volumes, otherwise the operation cannot succeed, and therefore one of the chief objects to be arrived at in ore dredging is to obtain the greatest possible capacity of ore washing treatment, having regard to the confined space upon the ore dredge within which this treatment must be accomplished, and the ability to successfully wash and recover the ore from the barren material after it has been disintegrated therefore becomes one of the limiting factors in ore dredge capacities.

The necessary limit in both floor space and head room which (along with accessory driving apparatus) can be made available for treatment apparatus on a floating pontoon, combined with the necessity for treatment of many thousands of cubic yards of material per day on a floating pontoon is one of the fundamental and inherent differences betWeen ore dredging, and all other mining operations, which has led to its development as a process'separate and distinct from allother branches of mining.

It follows therefore that one of the most important functions of the ore dredge should be to discard all of the worthless material possible, without undue loss of ore, before passing the resulting material on to the final ore saving devices on the dredge, so that any given unit of material handled by those devices will represent the greatest possible number of units of material as it originally stood in the bank.

In the ore dredging process as hitherto conducted, the practice has been to discard only the coarse barren materials direct to the waste heap, thus materially reducing the volume of material to be treated on the ore saving device, only when there is a large percentage of such coarse worthless classes in the original bank, but the antithetic step to accomplish the same object of reduction of bulk, viz that of discarding direct to the waste heap all of the finest sizes of barren sands, clays etc. possible, and by this fine discarding step to greatly reduce the volume, and at the same time to improve the character of the material that must be handled by the ore saving de-' vices, has not been practiced in the ore dredging process hitherto.

The essential steps in the treatment of the bank materials in the ore dredging process as hitherto conducted, are indicated in the drawlngs accompanying this specification in F 1gures 5 (an elevation View) and 6 (a plan view) in skeleton of an ore dredge, and are designated by the Roman numerals as given below. These essential steps are as follows I. The excavation of the material from the bank by bucket, suction cutter, gravel pump, or other type of excavators. 1 v

II. The disintegration of the material and the sorting out and rejecting, usually ,by means of screens or grizzlies, of the coarse gravel, boulders, rocks, and. other coarse grades of worthless materials, through taillngs elevators or stone shoots. III. Treatment of the whole of the'materials remaining after this preliminary sorting and coarse rejection step, upon sluices with rifiles as indicated, or upon other concentration devices. 1 c

The percentage of waste material that can be eliminated by the screening step depends entirely upon the coarseness of the material in the bank. Where there is a large percentage of coarse gravel, rocks, and boulders, as occurs in many placer deposits, then a large percentage of the original bank materials is eliminated by the screening process, and the, resulting quantity of material to be treated on the sluices, or other devices, is correspond ingly small, and large daily capacities of the. material as it originally stood in the bank can be successfully washed. Where however, the proportion of coarse material in the bank. is very small, and the percentage of the finest gravels, sands, and clays is correspondingly large, then the eliminating capabilities of the screening step without ore loss becomes almost nil, and practically the total quantity of the bank material that is brought on board the dredge must then be treated in the sluices or other concentrating devices. This results either in the overcrowding of those devices, and high ore losses, or in reducing the yardages handledfin order to prevent such over crowding and loss, and makes it impractical to handle the materials and make a close saving with such machines as jigs.

These smaller. sizes of material are invariably the most difficult to treat in large quantities in sluices or other ore concentrating devices, and at the same time to make a close saving of the ore contained. It is to overcome, this inherent weakness in the present ore dredging process, by the direct elimination of the finest sized materials before final treatment on the ore saving devices that the following improvement in the dredging process has been devised.

The steps in the improved process are as follows, again referring to Figures 5 and 6 of the drawings and the Roman numerals as below I. The excavation of the material by the ordinary bucket, suction cutter, gravel pump,

3r other type of dredge, as hitherto has been one.

II. The disintegration of the materials thus excavated, and the screening out and rejection of the coarse rocks, boulders, gravel or other coarse barren materials, as has hitherto been done. 7

II. The treatment of the ore bearing materials,-which result from the preliminary screening operation (step II above) and pass through the screen apertures, in a desanding, or classifying device, the essential object of which is to sort out and discard to the waste heap the worthless finer sands and slimes and to concentrate the valuable ore into the inter mediate sizes of materials, which intermediate sized material, only, is fed to the subsequent ore treatment devices, step III.

III. Treatment of the ore-bearing materials resulting from step II on sluices or other devices as has hitherto been done.

It will thus be seen that while the ordinary ore dredging process consists, after excavation, in the direct elimination of the coarser barren materials only, followed by the treat ment of all of the intermediate and finer grades of barren materials mixed up together, my improvement consists in the elimination of the coarsest, boulders, gravel and other barren materialsby means of screens as here? tofore, but follows this step by the further elimination of the finer classes of material designated as step II so that only the intermediate sizes of the material (as it stood in the bank) contain the ore, and this portion ofthe material only is treated by the final ore treatment devices; that is to say, that while the ore dredging process as hitherto practiced discards directly, before final treatment, only the coarsest sized classes of worthless'material, my improved process consists in the direct discard of both the coarsest and the finest sized classes, before conveying the medium sized "classes 'of bank material (i. e. the coarsest sands only) containing the bulk of the ore to the final ore treatment devices,

This elimination of the finer classes of worthless material accomplishes two very beneficial things which have hitherto not been accomplished in the ore dredging process viz: (A) It greatly reduces the bulk of the material to be handled on the ore washing devices by the removal of precisely those classes of barren material which are the greatest obstacle to rapid washing with a close saving of ore, and (B) it leaves the ore values in a greatly reduced bulk of material composed of the coarser classes of sands only; that is to say, material of the sort that can be most easily and rapidly washed on any large capacity efficient ore saving devices such as sluices, which are commonly in use on ere dredges, with a closer saving of ore than heretofore; and of such a character that it can also be handled in lower capacity ore saving devices which result in a closer saving than sluices as, for example, jigs, without clogging such devices with an unnecessary volume of worthless fine material.

In the elimination of the coarser sized materials, the screening devices in general use can be used. While in the succeeding step, the subject matter of my invention, that of eliminating the finer sizes of barren material, the well known rapid current, shallow box type of desanding device, known as spitzhasten, or sand wheels, or any other type of device which eliminates the worthless finer sands and, slimes from the ore bearing material before it is washed, may be used, but I prefer the use of a deep box, double current classifier because the capacity of this device, with equal classifying and settling qualities is greater than that of other forms of desanding, classifying and dewatering devices.

The drawings accompanying this specification make clear the nature of my improvement in which Fig. 1' is a plan view of the stern portion of a bucket type of ore dredge showing adeep boX double current classifier as the desanding apparatus, followed by jigs on the port side, and followed by ordinary sluices on the starboard side.

Fig. 2 is a cross-section on line B B of Fig. 1, showing the relations of the desanding apparatus to the treatment devices.

Fig. 8 is a longitudinal section of Fig. 1 on the line (AA) showing the desanding apparatus in combination with the jigs.

Fig. l is a longitudinal section on line CC of Fig. 1 showing the combination of the desanding device followed by ordinary ore sluices on the starboard side and jigs on the port side.

Figure 5 is a general sectional view of an ore dredge showing the sequence of fundamental treatment steps in the ore dredging process as heretofore practiced, and also with my improved process.

Figure 6 is a plan view of the dredge shown in Figure 5. In Figures 5 and 6 the fundamental steps only in the old and the improved process are indicated, and Roman numerals are used.

The following description makes clear the process bywhich the improvement is brought about. In this description and in the above figures the ordinary bucket type of dredge is used for purposes of illustration, but, it

will. be understood that the combination forming the improved method of treatment may be likewise used on suction cutter dredges on gravel pumps, or in other types of placer or alluvial ore dredging 0 erations.

Referring now in detail to the drawings, Figures 1 to 4 inclusive, in which the same reference numerals are used for the same parts, and in which the ordinary floating bucket type of ore dredge'is used for purposes of illustration. The ore bearing material is elevated by buckets (1) from iwhich it dumps into the feed shoot (2), and thence into the revolving screen, (3), in this revolving screen which is provided with perforations, the coarse rocks and gravel and other coarse extraneous materials are. screened out and dumped from the lower end of the screen into the stone shoot, or other discarding apparatus (4) from whence the coarser materials are discarded into, the pond or the waste heap at (5). In the ordinary dredging process the finer grades of materials which pass through the perforations in the screen issue from gates (6) under the screen, and thence all this fine material which has passed through the perforations in the screen passes directly on to the sluices (7) or other ore treatment devices, whence the waste material is discharged at 13 or at 14.

, The above is the description of the essential a are discarded in thetreatment process prior to the actual ore concentration operation, and that all materials which pass through the perforations in the screen, pass on for further treatment. in. the real ore concentation machines. These materials are essentially un-. classified other than by the very rough classification which is accomplished in the screening operation. Furthermore, the smallest sized holes practical to use in screens in dredging operations without clogging by small gravel and coarse sand grains are approximately to% of an inch in diameter.

It is therefore obvious that in thisjprocess only that portion of the bank material which is coarser than the diameters of the holes in the screen can be discarded direct into the tailings piles without being sent on to further treatment devices by means of which the final concentration is accomplished, and whose treatment capacities with close saving of ore are always limited. Accordingly where the great bulk of bank material is composed of fine sands whose grains are smaller than the holes in the screen (3), the percent of ma terial discarded by the screen becomes practically nothing. In other words the screen (3) in the .ordinary dredging process is the only machine for the elimination of waste material prior. to final ore treatment on the dredge,and in cases where there is no coarse treatment machines with the material, its function in this respect ceases,

ble coarse material has been removed by the screen as in the ordinary process, the resulting fine materials which havepassed through the apertures in the screen issue from the gates (6) under the screen and then by means of a feed launder pass directly into a desanding device (9) which may consist of the rapid current shallow box spitzkasten type orof sand elevators of any other type of desanding device, but preferably is of a deep box double current type, as indicated in the drawings. In thisclassifying or desanding step, and in the device shown, the finer sands and slimes are carried away from the desanding device (9) throughthe overflow (10) into the slime launders (11) from which they are discharged at (12). The coarser and heavier grains of sand and ore settle into the hoppers, a few of which are designated by the numeral (16) in the desanding device (9) according to their specific gravities, and pass out through the openings, a few of which are designated by the numeral (17) at the bottom, of the hoppers. These sizes of materials which carry sufficient percentage of oreare conveyed by the launders (18) to further treatment devices such as sluices 1 (7), or jigs (8).

It will be understood that in a classifier of the deep box double current type fresh water isintroduced so as to produce a second and lower current of fresh water under the current of pulp bearing water. This fresh water is available for use in the ore separation devices such as sluices or jigs, and is much more efficient than the thick, slimy water, such as in the upper current of the classifier.

It is obvious from the above description therefore that in my improved process all coarse materials which. the limitations of screening permit, will be discarded directly into the waste heap by means of the screen (3) as heretofore, and that following this discarding step, all of the finer worthless materials which may be separated from the valuable minerals by means of the rates of settling in water prior to final treatment, are likewise discarded directly to the waste heap, without going to further concentration devices; and these devices are thus relieved from treating this fine material, which is the most diflicult sort of material for them to treat in large capacities. It is also obvious that the bulk of the material to be treated in the ore saving machines will be much reduced as compared with the bulk that must be treated in the present ore dredging process, that is to say that any given unit of materialhandled by the ore saving machines will represent a much greater quantity of the bank material than has hitherto been possible, and the real capacity of the ore saving devices, asrelated to the bank material being worked, will thereforebe greater than heretofore, and also a closer saving of ore can be made. i

It is also obvious (if classifiers are used), that there will be a definite classification of the sands and ore caught, into various sizes, which may be taken on for further treatment to the devices adapted to best handle the different sizes; these devices may then work to their maximum capacity both in ore saving and in material treated.

By means of my improvement in the meth- 0d of handling the material therefore the bulk of the material carrying the ore, which must be treated in the ore saving machines, will be so improved in character and reduced in volume that it can be treated with closer ore saving and greater eificiency on such large capacity devices as the present type of sluices than has hitherto been possible, and so that other well known lower capacity but close ore saving machines as for example jigs, which have hitherto been unsuccessful on dredges working fine sandy and clayey alluvial deposits, can successfully treat the material, all of whichwill result in larger working capacities and closer saving of ore than have been hitherto possible, and the chief objects of the improved method of treatment will be thus attained.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be per: formed, I declare that what I claim is 1. The process of ore dredging comprising excavating the material, separating and rejecting the coarsest and the finest classes of the excavated material and treating the remaining intermediate classes of the mate rial to recover the valuable metal therefrom after the coarsest and finest classes have been removed.

2. The process of ore dredging comprising excavating the material, separating and discarding the coarse classes, separating and discarding the fine classes and classifying the intermediate classes into separate and different intermediate classes.

3. The process of ore dredging comprising excavating the material, separating out and rejecting the coarse classes, separating out and rejecting the fine classes by carrying them oil in a current of water, and treating the intermediate classes with fresh water after the coarse classes and fine classes have been removed.

l. The process of ore dredging comprising excavating the material, separating out and rejecting the coarse classes, separating out and rejecting the fine classes by carrying them oil in a currentof water, and treating the intermediate classes in ore separation devices azfiter the coarse classes and fine classes have been removed.

5. The process of ore dredging comprising excavating the material, separating out and rejecting the coarse classes, separating out and rejecting the line classes by allowing the current of water in which they are suspended to carry them oil, causing a current of fresh water to flow under said first current, the intermediate classes leaving said first current passing through said second current, and treating the intermediate classes with said fresh water after the coarse classes and fine classes have been removed.

6. The process of ore dredging comprising excavating material,-se )arating out and rejecting the coarse classes, separating out and rejecting the fine classes by allowing the current 01" water in which they are suspended to carry them ofi", causing a current of fresh Water to flow under said first current, allowing the intermediate classes leaving said first current to pass through said second current, classii ying said intermediate classes into separate and different intermediate classes according to their rates of settling in said currents, and treating the intermediate classes with said fresh water after the coarse classes and fine classes have been removed.

7. An apparatus for recovering metal from submerged metal bearing deposits comprising a float adapted to beheld adjacent said deposits, means on the float for excavating the material of the deposit, means on the float for screening out the coarse classes from the excavated material, a deep box double current classifier on the float for carrying off the fine classes in a current of water and allowing the difl'erent intermediate classes to settle into different hoppers, and metal saving devices on the float for recovering the metal from said intermediate classes after the coarse and fine classes have been removed.

8. An apparatus for recovering metal from submerged metal bearing deposits comprising a float adapted to be held adjacent said deposits, means on the float for'excavating the material of the deposit, means on the float for rejecting the coarse classes from the excavated material, means on the float for rejecting the fine classes by carrying them off in a current of water, and metal saving devices on the float for recovering the metal from the remaining intermediate classes after the coarse and fine classes have been removed.

9. An apparatus for recovering metal from submerged metal bearing deposits comprising a float adapted to be held adjacent said deposits, means on the float for excavating the material of the deposit, means on the float for rejecting the coarse classes from the excavated material, means on the float for rejecting the fine classes, and metal saving devices on the float for recovering the metal from the remaining intermediate classes after the coarse and fine classes have been removed.

10. An aparatus for recovering metal from submerged metal bearing deposits comprising a float adapted to be held adjacent said deposits, means on the float for excavating the material of the deposit, means on the float for rejecting worthless classes including the fine classes from the excavated material, and metal saving devices on the float for recovering the metal from the remaining intermediate classes after the worthless classes have been removed.

11. An apparatus for recovering metal from submerged metal bearing deposits com prising a float adapted to be held adjacent the submerged deposit, means on the float for excavating the material of the deposit, a classifier on the float having a series of hoppers, means for causing the material of the deposit and water to flow through said classifier to allow the different intermediate classes to settle into the several hoppers and to allow the fine classes to be carried away by the water, a plurality of jigs on the float for treating the intermediate classes delivered by said hoppers to recover the values therefrom.

12. An apparatus for recovering metal from submerged metal bearing deposits comprising a float adapted to be held adjacent the submerged deposit, means on the float for excavating the material of the deposit, means on the float for separating out and rejecting the worthless classes including the fine classes, and jigs on the float for treating the remaining intermediate classes to recover thevvalues therefrom after the worthless classes have been removed.

13. An apparatus for recovering metal from submerged metal bearing deposits comprising a float adapted to be held adjacent the submerged deposit, means on the float for excavating the material of the deposit, means on the float for separating out the worthless classes including the superfine slimes, fine sands and excess Water from the material of the deposit, and jigs on the float to treat the valuable intermediate classes after the worthless classes have been removed.

14. An apparatus for recovering metal from submerged metal bearing deposits comprising a float adapted to be held adjacent the submerged deposit, means on the float for excavating the material of the deposit, a deep box double current classifier on the float, devices for rejecting the Worthless classes including means for causing material of the deposit and water to flow through said classifier to allow the fine classes and excess water to flow over- JOHN FLESHEB NEWSOM

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