Much interest is being shown by both small operators and big mining companies in small portable and semi-portable milling plants. The small operator, perhaps lacking an extensive ore deposit or finances, must rely on a layout low in initial cost. The bigger mining companies are interested in these small plants—because they can economically prove certain ore bodies with standard mill units.

Below are four typical flowsheets. It is comparatively easy to choose the flowsheet desired for your particular ore problem. These layouts incorporate standard items of equipment. One main advantage lies in their portability and the fact that equipment can be sectionalized for muleback transportation. When it becomes necessary to move to another location very little is left behind. The steel structure is so arranged that you can change the flowsheet as desired. Machines can be added as required without major alterations. Certain parts of machines are standard and are in the same location for all flowsheets.

**Flowsheet of Portable Mineral Processing Plant A**

This layout is ideal for recovery of gold. It involves an all gravity concentration principle. A high recovery can be expected when treating a free-milling gold ore. The grinding is done in a 30″ x 18″ Convertible Ball Mill in open circuit. The size of product can be controlled by a Spiral Screen on the ball mill discharge. The screen has a reverse spiral to prevent grinding balls and very coarse ore from coming out of the unit. The Selective Mineral Jig recovers the values as coarse as possible, as soon as freed from the gangue. The jig tailings are passed over a half-size Wilfley Concentrating Table where a final concentrate is made. The table middlings may be returned to the ball mill for regrind if desirable. Approximate shipping weight of all of the above items including bins and steel structure is 17,600 pounds. Approximate H.P. required: 13. Capacity: 5.7 tons per 24 hours.

**Flowsheet of Portable Ore Processing Plant B**

This flowsheet lends itself to a one mineral separation by flotation. The grinding is accomplished by a 30′ x 18″ Convertible Ball Mill with a Spiral Screen at the discharge. The Unit Flotation Cell in the ball-mill-classifier circuit recovers a high percentage of the coarse mineral values. The classifier overflow goes to a 4-Cell No. 8 (16 x 16) “Sub- A” Flotation Machine. The flotation tailings are passed over a Wilfley Concentrating Table. This table serves not only as a scavenger but a visual sampler. The operator can see with his own eyes what results he is getting and can make immediate adjustments if necessary. This simple and flexible layout is recommended where the problem is one of bulk flotation. Approximate shipping weight, including bins and steel structure: 18,200 pounds. Approximate horsepower required: 17. Capacity: 5-7 tons per 24 hours.

**Flowsheet of Portable Mineral Processing Plant C**

Perhaps the most common milling problem is the one involving a two mineral separation by flotation. Most common of the ores subjected to this treatment are lead and zinc. This circuit will do an efficient job of solving most such problems. In order to increase the grinding capacity, a shell extension has been added to the 30″ Convertible Ball Mill, making a 30″x 36″ unit. This can be accomplished at a slight additional cost over the original 30″ x 18″ mill. High recoveries of lead can be expected in the Unit Flotation Cell in the ball-mill-classifier circuit. The first bank of “Sub-A” Flotation Cells recovers the balance of the lead values recoverable by flotation. The tailings from the lead machine are conditioned in a 3′ x 4′ Super-Agitator and Conditioner where reagents for activation of zinc are added. The flexibility of the ’’Sub-A” Flotation Machine allows any cell to be used as a rougher, cleaner or recleaner— an indispensible feature in small mills.

Approximate shipping weight is 30,000 pounds. Approximate H.P. required: 27. Capacity: 7-10 tons per 24 hours.

**Flowsheet of Portable Ore Processing Plant D**

This flowsheet has been designed for treatment of tungsten and similar friable ores that can be treated by gravity concentration. Care must be taken not to overgrind the values which would result in sliming and eventual mineral loss. For this reason a 30″ x 54″ Convertible Ball Mill with a grate discharge is used in this all gravity concentration plant.

A Duplex Selective Mineral Jig recovers the values as soon and as coarse as possible. The jig tailings go to a Hydraulic Classifier where two sized products are produced. Each of these products is fed to a separate Wilfley Concentrating Table where final concentrates are obtained. The table middlings can be returned to the ball-mill for regrind if necessary.

Approximate shipping weight (not including ore bin) is 21,800 pounds. Approximate H.P. required: 19. Capacity: 10-15 tons per 24 hours.

**A five-ton per hour Portable Mill 5 TPH**

**Source:**

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