C$)$ In the Silver Cobalt flowsheet description below from Denver Equipment, list each of the types of unit operations used. What is separated in the gravity concentration unit operation? What is separated in the froth flotation unit operation?

GRAVITY AND FLOTATION OF SILVER$-$COBALT

The Problem

The treatment of complex silver$-$cobalt ores occurring with antimony

jaw crusher product and conveyed to a double$-$deck DENVER Vibrating Screen. The top deck scalps off the coarse fraction and protects the plus near mesh. All screen undersize is conveyed to the fine ore bin. The secondary crusher product discharges to the common conveyor handling the grizzly undersize and the primary jaw product.

Grinding SECTION$-$Two stage grinding is used. The fine ore is fed directly from the ore bin by a DENVER Belt Ore Feeder to a Denver Rod Mill equipped with a DENVER Spiral Screen to remove tramp material. A head sample is removed from the feeder trajectory by a DENVER Automatic Sampler. The primary grind in the rod mill is approx. $10$ mesh. The undersize discharged from the DENVER Rod Mill Spiral Screen is treated in a duplex DENYER Selective Mineral Jig where coarse free silver is recovered. The DENVER Mineral Jig is capable of handling an unclassified feed and is an ideal unit for the grinding circuit. The primary jig tailings flow to a DENVER Spiral Classifier.

The classifier sands discharge by gravity to the ball mill scoop box. The DENVER Ball Mill with trunnion overflow discharge is also furnished with a DENVER Spiral Screen and the screen undersize is the feed for a second DENVER Mineral Jig. Both the Rod Mill Jig and the Ball Mill Jig tailings flow by gravity to the DENVER Spiral Classifier. Two stage grinding, and gravity concentration aids recovery of values as soon as freed and precludes the possibility of loss of mineral due to overgrinding and sliming.

The jig hutch products which contain extremely high silver and cobalt values, represent approximately $65\%$ of the total silver recovery and $80\%$ of the cobalt recovery. Jig concentrates discharge continuously by means of a DENVER Dowsett Density Valve and are dewatered, and dried for shipment to the smelter.

Gravity Table Concentration Section $-$ The minus $48$ mesh classifier overflow at $30\%$ solids by weight is transferred by a DENVER SRL Pump to a Self Rotating DENVER Pulp Distributor which feeds the DENVER Concentrating tables. All table concentrates are combined with the jig hutch products for drying and shipment. The table middlings and tailings are pumped to a DENVER Spiral Rake Thickener. The thickener underflow at $28\%$ solids is effectively metered to the flotation section by a DENVER Adjustable Stroke Diaphragm Pump. All reclaimed water from the thickener overflow is pumped to a constant head mill water tank. Denver Vertical Centrifugal Sand Pumps are employed for silver$-$cobalt table concentrate handling.

FLOTATION SECTION$-$Preparatory to flotation, the thickener underflow pulp is conditioned with reagents in a DENVER Super Agitator and Conditioner. All chemical additives are metered by DENVER Reagent Feeders. The conditioned slurry flows to a cell$-$to$-$cell DENVER "Sub$-$A$"$ Flotation Machine comprised of ten cells arranged as seven roughers and three cleaners. Flex$-$

ibility provides that one or more of the three cleaners could be used as a recleaner depending on the mill feed.

A final tailing is discharged from the seventh rougher cell, is sampled by a DENVER Automatic Sampler, then pumped by a DENVER SRL to the tailing pond.

The rougher flotation concentrate flows by gravity to the number one or number two cell for cleaning. If recleaning is indicated the concentrates from cells Nos. $2$ and $3$ are returned by gravity as feed to No$.1$ cell.

Thickening and Filtration$-$The cleaned silver concentrate is densified in a DENVER Concentrate Thickener to $65\%$ solids. The underflow is handled by a DENVER Adjustable Stroke Diaphragm Pump and fed to a DENver Disc Filter. The and arsenic require special metallurgical processing to produce concentrates most advantageous for smelting. Gravity concentration is used to initially recover a high percentage of the native silver and cobalt. The concentrate is marketed and payment received for these constituents. Flotation treatment of the gravity tailing recovers additional silver values for marketing at a separate smelter

The Flowsheet

In this study, the silver occurs essentially as impure native silver together with argentite, cobaltite and other complex sulfides. The flowsheet is based on a $400$ ton per day concentrator with special emphasis on "recover your mineral as soon as free."

CRUSHING SECTION $-$ The conventional two stage crushing plant has a rated capacity in excess of $200$ tons per $8$ hours.

The grizzly undersize $(2\frac{1}{2\text{'}\text{'}})$ is combined with the

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