Every ore is distinctive and presents its own individual problems in profitable mineral recovery. 911Metallurgy’s experience in treating the many different ores submitted to our laboratories assures the development of the best treatment with most economical and profitable recovery. This will prevent any “weak links” and makes your mill make money.

911Metallurgy strives to develop the simplest flowsheets even in complex problems to give you optimum return for your investment. There are undoubtedly many ore dressing methods for a particular ore, but the practical solution produces milling economy and profits. 911Metallurgy flowsheets also provide FLEXIBILITY for changing conditions.

Getting into production quickly means greater profit. By centralizing your purchases with one manufacturer, you save money and simplify labor problems at the mill site. Unit and Portable Mills are especially valuable in enabling you to get into production quickly with a minimum of design problems or construction difficulties.

911Metallurgy has had a great deal of experience in mill design, construction and operation. We are happy to offer your engineers the benefit of this “know-how.”

Introduction to Mineral Processing Concentrator Design

During the past 15 or 20 years, the trend in exploiting ore bodies has been toward larger and larger plants to handle increasingly lower grade, but larger, ore bodies. Smaller, but higher grade, ore bodies have been neglected because they did not contain sufficient ore reserves to warrant installation of a permanent mill and they could not be mined at a grade high enough to ship directly to the smelter at a profit.

Today, however, more effort is given to producing ores which usually do not occur in large deposits, such as columbite-tantalite, beryl and others which are becoming more important. The increasing use of portable and semi-portable mills—which offer mobility with a minimum of cost, time and loss of initial investment—has played a very important part in recovering these ores.

PORTABLE CRUSHING UNITS

PORTABLE BALL OR ROD MILLS

PORTABLE FILTER UNITS

These portable units are being successfully used for exploiting small ore bodies and for pilot plant installations on large ore bodies.
The chief advantages in using Portable Mills for pilot plant work in developing a large ore body are:

First, the three persons most closely involved in developing the project successfully—the geologist, the mining engineer and the metallurgist— are able to work closely together in solving the problems of exploiting the ore body to greatest advantage;

Second, it eliminates, to a great extent, the possibility of having to work with inaccurate or misleading samples, as may easily happen with small sample batch testing.

Other decided advantages are:

the great saving in development time,
improved mill design, and
production of profit-making concentrates during development.

The mills shown in this bulletin are standard designs with flowsheets flexible enough to readily adapt to most problems. If you have a special problem, 911Metallurgy can design and build a mill to meet this special need.

List of Equipment—100 Ton Mill

Fine Ore Bin…………………………………………..16′ x 16′
Adjustable Stroke Ore Feeder……………………20″ width
Automatic Sampler………………………………….16″ or 21″
Steel-Head Ball Mill………………………………….5′ x 8′
Spiral Classifier……………………………………….36″ x 17′-2″
Unit Cell………………………………………………..No. 500
Vertical Centrifugal Sand Pump (4)……………2″
Super-Agitator (2)……………………………………6’x 6′
Wet Reagent Feeders (4)……………….No. 12-A
“Sub-A” Flotation Machines (2)…………………No. 18 Sp.
Tray Thickener……………………………………….2 compartment
Disc Filter………………………………………………4’—4 disc

The drawings on these pages clearly show the wisdom of planning your mill to permit expansion in production without sacrificing equipment or going through a costly downtime while a new mill is being installed.

On this page is the basic mill for handling up to 100 tons a day. All equipment is standard, reliable 911Metallurgy machines, designed for 24 hour a day service.

The facing page shows the same basic mill, but with equipment added, as indicated in color, for 200 tons a day production. The new units can be installed without interfering with production for a long period. Operation with the machines in the basic mill will have familiarized all personnel with them so there will be no “trial and error” period.

EXPAND & Add Equipment for 200 Ton Mill

Steel Head Ball Mill……………………………………………..5’x 5′
Super-Agitator (2)……………………………………………….6’x 6′
Duplex Wet Reagent Feeders………………………………..(4) No. 12-A
8-cell “Sub-A” Flotation Machines………………………..(2) No. 18-Sp.
Vertical Centrifugal Sand Pumps…………………………..(2) 2″
Automatic Sampler
Disc Filter………………………………………………………….4′-4 disc
Tray Thickener…………………………………………………..2 compartment

Complete Milling Equipment—from Testing, to Feeder to Dryer

LIST OF EQUIPMENT—100 TON MILL

Fine Ore Bin…………………………………………………….16′ x 16′
Type “H” Jaw Crusher……………………………………….10″ x 16″
Conveyor Belt………………………………………………….16” wide
Dillon Vibrating Screen…………………………………….2′ x 3′
Cone Crusher………………………………………………….18″ dia.
Adjustable Stroke Ore Feeder……………………………20″ wide
Automatic Samplers (3)
Steel-Head Rod Mill………………………………………..4′ x 8′
Spiral Classifier……………………………………………….36″ x 17′-2″
“Sub-A” Unit Flotation Cell……………………………..No. 250
Vertical Sand Pump (3)……………………………………2″
Wet Reagent Feeder (2 duplex)…………………………No. 12-A
10-cell “Sub-A” Flotation Machine…………………….No. 18 Sp.
Super-Agitator……………………………………………….5′ x 5′
Wilfley Pilot Table………………………………………….No. 13-B
Disc Filter……………………………………………………..4’—2 Disc
Blower and Vacuum Pump for Filter
Diesel Electric Generator………………………………..D364
Concentrate Bin No. 1…………………………………….12’x 12′
Laboratory Sampling Equipment

EQUIPMENT FOR 2x ADDED CAPACITY

21. Steel-Head Ball Mill…………………………………………….4′ x 5′
22. Super-Agitator……………………………………………………5’x 5′
23. Duplex Wet Reagent Feeders (2)
24. 10-cell “Sub-A” Flotation Machine……………………….No. 18 Sp.
25. Vertical Sand Pump……………………………………………2″
26. Disc Filter………………………………………………………..4’—4 Disc
27. Automatic Sampler
28. Electric Generator…………………………………………….D364
29. Concentrate Bin No. 2……………………………………….12’x 12′

Each Portable Mill is completely erected at our shops and each part is match-marked before dismantling and packing for shipment. The mill shown is a standard 25-35 ton per 24 hours unit. Note the location of the Disc Filter above the concentrate storage bins.

The standard Unit Mills are supplied in three capacity ranges: 25-35 tons per 24 hours, 50-65 tons per 24 hours and 100-125 tons per 24 hours.

All models are extremely flexible in flowsheet design, combining both gravity and flotation concentration so that either section may be used alone or in conjunction with the other to produce the most efficient and profitable results.

These Portable Mills are of bolted construction, with all elements match-marked so they can be readily assembled or dismantled by the operators. Complete drawings and instructions are supplied, as well as operating instructions for the machines.

The plan and elevation views of the mill shown on page 9 indicate the plant arrangement for the Portable Mill of 25-35 ton capacity, arranged for gravity and flotation concentration. The arrangement is flexible enough, however, to adapt to new operating requirements as they arise.

(Top Left) A Portable Mill in the yard at the shops undergoing examination and match-marking before crating for shipment. Note the efficient layout of equipment to utilize maximum flexibility of the flowsheet. Bins shown are for concentrate storage.

(Top Right) Grinding section on lower floor of portable mill shows a Type “E” Steel-Head Ball Mill with Spiral Screen on discharge end, Cross-Flow Classifier, “Sub-A” Unit Flotation Cell and two Vertical Centrifugal Sand Pumps. The “Sub-A” Flotation Machines are on the floor above. All machines in this mill are standard, full-scale units.

(Bottom Left) Bolted steel I-beams for mill base are easily assembled or dismantled in the field, yet provide a sturdy base for mounting the machines and supporting the framework.

(Bottom Right) A Selective Mineral Jig is installed in the grinding circuit to recover mineral as soon as freed from unclassified ball mill discharge, after which pulp is fed to the Unit Cell. Pump elevates unit cell concentrate to filter on top deck.

PLANT GENERAL ARRANGEMENT (For Gravity and Flotation Concentration)

Wilfley Concentrating Table is operated off the mill platform, in this case to handle tailings from the “Sub-A” Flotation Machine. It may also be used to table jig tailings in straight gravity concentration.

A Portable Truck Mill ready for transporting. The water tank and top of bucket elevator have been removed and side platforms lifted. These simple steps are all that need be done to prepare the mill for shipment.

Compact arrangement of the Portable Truck Mill is clearly shown in this general view.

Portable Mill receives final inspection before shipment from factory. Note that mill framework permits user to install any type of roofing he desires.

View of mill from feed end shows the Type “H” Jaw Crusher, Bucket Elevator, mill water tank (above) and crushed ore bin (below). Water tank and top of elevator can be removed to allow transporting.

Central control panel is equipped with master control switch and individual machine circuit breakers. Starting switches are located near each machine. Complete wiring is included with each Portable Mill.

Flowsheet No. 1 is for an all-gravity mill. Two Wilfley Concentrating Tables and a Selective Mineral Jig make this a very efficient gravity unit.

Flowsheet No. 2 is an all-gravity circuit primarily used for gold recovery.

Flowsheet No. 3 is flexible enough to handle most types of ore dressing problems. It permits gravity concentration, flotation, or a combination of gravity and flotation methods. This is particularly useful for pilot plant work or for exploiting deposits in a number of places.

Flowsheet No. 4 is used for selective flotation concentration of two minerals. It makes full use of the flexibility of the “Sub-A” Flotation Machine by permitting the operator to use any cell as a rougher, cleaner or recleaner and allowing return of middlings to any cell in the circuit. The Unit Cell provides recovery of coarse mineral as soon as it is free, thus reducing losses due to sliming. For concentrating more than two minerals additional flotation cells may be added.

The 7-10 ton per 24-hour Portable Truck Mill is compactly arranged for maximum efficiency and ease of operation. Machines in crushing, grinding, classifying and flotation sections shown here are all standard, full-size units.

Each Portable Truck Mill also includes water tank, pumps, Caterpillar Diesel Electric Set, wet and dry reagent feeders where applicable and complete launders, piping and electrical wiring.

PORTABLE MILL 5-7 TON

This Portable Mill was designed for use at a mine in Bolivia and utilizes a Diesel Power Plant with belt drives. All small Mills can be supplied with this arrangement if desired.

This mill is constructed so that there is extreme flexibility of operation. Additional machines can be added as desired, such as a second 18″ diameter shell to the Ball Mill, another 2-cell flotation machine, a second classifier if required, etc.

LIST OF EQUIPMENT

1—5″x 6″ Type “H” Jaw Crusher
1—Belt Ore Feeder
1—30″x 18″ Ball Mill
1—Spiral Screen
1—4″x 6″ Selective Mineral Jig
1—6″x 6′ Drag Classifier
2—2-cell No. 8 “Sub-A” Flotation Machines
1—4-compartment Midget Wet Reagent Feeder
1—6″ Cone-Type Dry Reagent Feeder
1—No. 12-S Wllfley Concentrating Table
1 Ore Bin, 1 Welded Steel Water Tank, Steel Structure, Transmission Equipment, Launders and Piping and 1 Model D-311 Caterpillar Diesel Engine.

PACKAGE COAL FLOTATION UNIT

Recover high grade, salable coal economically from coal washery effluent, dry preparation dust collectors, settling basin overflows, silt banks in rivers or waste fines from all preparation plants.

This complete plant economically handles material as coarse as ¼” to produce a matte type high grade product with low moisture. There are no installation problems and operation is simple and trouble-free. High capacity units available, in addition to 2½, 5, 10 or 20 ton/hour units.

PORTABLE PLACER UNITS

25 OR 50 CU. YDS. PER HOUR
The Portable Placer Unit comes in two models, one handling 25 cubic yards an hour and the other 50 cubic yards an hour. It is a more flexible machine than the dredge type unit, as it does not require a large pond for operation.

LIST OF EQUIPMENT

Feed Hopper with Chute
Nugget Trap
Revolving Scrubbing Trommel
16″x 24″ Duplex Selective Mineral Jig (Rougher)
Dewatering Screw Conveyor
8″x 12″ Duplex Selective Mineral Jig (Cleaner)
2 Vertical Centrifugal Sand Pumps
24″x 36″ Amalgamation Unit
Caterpillar Diesel Electric Set
24″x 30L Portable Stacking Conveyor

PORTABLE CYANIDE MILLS

Modern cyanide plant design, anticipating increase to double original capacity by adding a second grinding circuit and filters in the same building space. The primary crushing plant (not shown) utilizes single-stage crushing. For the doubled capacity, a secondary crusher and screen are added.

PORTABLE GOLD MILL

Photo shows the grinding, classification and amalgamation section of a two part portable mill designed for use and still operating in Mexico after more than ten years. This unit was supplied with a belt drive because of the remote location of the property, where the only power available was from the Diesel power unit.

MECHANICAL GOLD PAN WITH TROMMEL SCREEN

This unit is similar to the Trommel-Jig Placer unit in that mineral values are washed and separated in the trommel screen. The freed sands are then fed to a Mechanical Gold Pan, where both the coarse and fine gold values are concentrated with an action duplicating hand panning.

TROMMEL-JIG GRAVITY UNIT

This compact gravity unit combines a trommel screen—for separating the fine mineral values from clays and coarse gravels—with a Selective Mineral Jig, which separates valuable heavy minerals from lighter gangue. A centrifugal water pump provides water for the trommel screen and the jig.

The entire unit is mounted on a steel skid base with angle iron framework. Steel sides (not shown) are provided to protect the unit. Three different sizes are available with a capacity range from 1 to 6 cubic yards per hour.

HOW TROMMEL JIGS HELPED DEVELOP SMALL MINE

Two No. 6 Trommel Jig units were effectively used during the development of a lead mine in Mexico. The trommel jig units were operated 8 to 10 hours a day. Each unit handled from 6-8 metric tons of ore, producing 1.3 to 1.7 metric tons of concentrates. As shown on the flowsheet below, the combined concentrates from the Jigs and hand jigs, plus the lead from hand picking, averaged in excess of 70% lead with about 90% recovery.

Design and construction of the Mill incorporated facilities for future expansion of operations.

This 5’x 5′ Steel-Head Ball Mill handled 50-70 tons per day in the initial installation.

An inexpensive extension of the 5′ x 5′ mill added a 2′ shell section to permit handling 40% more tonnage.

Two “Sub-A” Flotation Machines are provided for producing high grade lead and zinc concentrates.

Source: This article is a reproduction of an excerpt of “In the Public Domain” documents held in 911Metallurgy Corp’s private library.