Mineral Processing Engineering

Grinding Mill Design & Ball Mill Manufacturer

All Grinding Mill & Ball Mill Manufacturers understand the object of the grinding process is a mechanical reduction in size of crushable material. Grinding can be undertaken in many ways. The most common way for high capacity industrial purposes is to use a tumbling charge of grinding media in a rotating cylinder or drum. The fragmentation of the material in that charge occurs through pressure, impact, and abrasion.

Grinding is converting energy: When the grinding charge is forced to tumble the motor energy is converted into new particle surface and heat.

An important point for the economy is that the size of the grinding media suits the material to be ground.

The choice of mill design depends on the particle size distribution in the feed and in the product wanted. Often the grinding is more economic when executed in a primary step, followed by a secondary step, giving a fine size product.

As experts in crushing and grinding – can offer a full range of grinding mill types and sizes. Our mills are identified by codes of letters:

C=central trunnion discharge
P=peripheral discharge
R=spherical roller trunnion bearing, feed end
H=hydrostatic shoe bearing, feed end
R=spherical roller trunnion bearing, discharge end
K=ring gear and pinion drive

CRRK

By | 2017-04-28T00:08:53+00:00 February 20th, 2017|Categories: Crushing & Screening|Comments Off on Grinding Mill Design & Ball Mill Manufacturer

How Ball Mill Ore Feed Size Affects Tonnage & Capacity

The important of crushing your ore and rock fine and properly is often forgotten. The finer you crush, the higher your ball mill tonnage and capacity will be.  The effect of ball mill feed size and how it affects circuit throughput can be hard to estimate. Here we described a method of designing a crushing plant using power drawn and power rate to define reduction ratios in each stage of crushing. The plant power and power rates were computed from a Bond calculation as applied to the crushing plant feed and output sizes. A comparison of the low and high energy configurations.

We would design this plant differently today using energy parameters from the pendulum impact tests for calculations. It would only be necessary to use the Bond feed and product size calculation if no pendulum results were available.

Crushing Finer To Reduce Milling Costs

This new high energy or power rate crushing brings a different perspective to comminution flow sheet selection. Generally, up until the early 1960’s the classical flow sheet for a beneficiation plant was primary crushing followed by two stages of cone crushing in closed or open circuit, making feed for rod mills, followed by ball mills. The rod

By | 2017-07-26T12:01:49+00:00 July 26th, 2017|Categories: Crushing & Screening|Comments Off on How Ball Mill Ore Feed Size Affects Tonnage & Capacity

Knelson Concentrator

The Knelson Concentrator relies on an enhanced gravitational force together with fluidization process to recover even very micron sized particles. First water is injected into the rotating concentrating cone through series of fluidization holes. Then feed slurry is introduced through a stationary feed tube. Once the slurry is filled in each cone, create a concentrating bed and high specific gravity particles are retained in the cone and then flushed into the concentrate launders. This procedure can be completed in less than one minute.

The Knelson concentrator (KC) is a vertical axis bowl-type centrifugal concentrator that uses a fluidized bed to perform its concentrating duty. It was first introduced as a semi-batch unit and has gone through several iterations of design leading to the development of a continuous discharge machine. It has now become almost an essential unit operation in any gold processing plant to assess the gravity recoverable gold content in the ore as well as to recover fine free gold from the grinding circuit.knelson gold concentrator (1)

Knelson Concentrator (KC) first introduced to the hard rock milling industry there-by providing gold recovery by handling a maximum feed size of 6 mm. More recently KC-XD30 is

By | 2017-07-26T18:23:30+00:00 July 24th, 2017|Categories: Gravity Concentration|Comments Off on Knelson Concentrator

Recovery of Cadmium from Scrap Batteries

The manufacture and use of nickel-cadmium alkaline batteries began to grow in the late 1950’s. During the period from 1966 to 1971, approximately 3 pct of the U.S. primary cadmium demand was consumed by battery manufacturers. From 1971 to 1975, the demand grew from 3 pct to 13 pct. It was estimated by the battery manufacturers (1) that by 1981 2.2 million pounds, or greater than 20 pct of the yearly U.S. demand for cadmium, will be consumed by battery manufacturers. The United States is dependent on Canada, Mexico, and Australia for greater than 60 pct of its primary cadmium supply.

At present, there is no commercial process being used in the United States to recover the total metal values from Ni-Cd battery scrap. Virtually all of the scrap recovered is shipped overseas, where it is processed and returned to this country as refined metals. Several scrap dealers are breaking the battery cells and hand-separating the positive and negative plates. The positive plates, containing 1 to 2 pct cadmium, are smelted in the United States to a high-ferro nickel alloy. The cadmium-rich negative plates are shipped overseas.

schematic-of-retort-condenser-system

As part of its efforts in secondary

By | 2017-07-24T14:46:31+00:00 July 24th, 2017|Categories: Uncategorized|Comments Off on Recovery of Cadmium from Scrap Batteries

Rock Splitting

Rock splitting utilizes a tensional force to crack the rock. This is achieved by inserting a split steel shank in a drillhole and driving a steel wedge between the center of the split shank thereby producing the tensile forces.

The advantages of the rock splitting technique over blockholing are the absence of explosives and the reduction of downtime provided there is quick and easy access to the rock splitting equipment.

The rock splitting technique does have some disadvantages. Drilling the required hole is time consuming and hazardous. Before any drilling is done, the boulder should be examined for stray powder and for the best hole location. The boulder, probably containing cracks from the primary blast, will be hazardous to drill in that, it could split without warning. When actually splitting the rock with the splitter, a safe place on the boulder must be available to work from so as to avoid injury. Alternatively the procedure may be done by remote control whereby the operator is removed from the breaking area.

One type of rock splitting machine is illustrated in Figure 13. This hand held device utilizes hydraulic pressure to expand a plug placed in a drillhole creating tensile failure in the rock. The

By | 2017-07-24T12:50:00+00:00 July 24th, 2017|Categories: Crushing & Screening|Comments Off on Rock Splitting

Rock Grapple

A rock grappler is a claw shaped device used for picking up boulders. The grasping mechanism of a grappler is generally activated by a pneumatic or hydraulic cylinder, as shown in Figure 17. The cylinder is connected to each half of the claw and when activated forces the claw shut. Grapplers are used to remove or reposition boulders; they can only break rock by lifting and dropping.

There are two types of lifting mechanisms that can be used with the grappler claw. One requires that the claw be mounted on the end of a large hydraulic boom. This gives the grappler good mobility and good response to controls.

The problem with this mechanism is that an extremely strong and large boom is needed. The other lifting mechanism is an overhead crane system which uses cables and pulleys. This mechanism is strong, but is slow and difficult to maneuver into the desired position.

stone crusher efficiency grapplers

A grappler is most commonly used with a gyratory crusher because of the greater difficulty of access to a jaw, impact, or roll crusher (refer to figures 5 through 8). A grappler is a capital intensive piece of equipment but

By | 2017-07-24T12:48:33+00:00 July 24th, 2017|Categories: Crushing & Screening|Comments Off on Rock Grapple

How to Unplug Crusher

A sling is a device for removing or repositioning a boulder or object in a crusher. A sling is made of a length of chain or cable with loop ends as shown in Figure 18c. To remove or reposition a boulder a sling is laced around the boulder and the looped ends are connected to a boom, winch, or overhead crane and hoisted out of the crusher or moved to where the crusher can nip it. The advantages to this method are the protection to the crusher parts because explosives are not used. The disadvantages are that the crusher has to be stopped, a person has to get in the crusher, and the length of time to move or remove the boulder can be excessive. Also, if an angled grizzly feeds the crusher, it must be cleaned of all loose debris before someone can enter the crusher mouth. Operators have spent as much as half a work shift doing this task.

stone crusher efficiency sling and hooks

A hook is a device which is primarily used for re-positioning the boulder. Some of the more efficient hooks are shown in Figures 18a and 18b.

The hooks

By | 2017-07-24T12:40:29+00:00 July 24th, 2017|Categories: Crushing & Screening|Comments Off on How to Unplug Crusher

Rock Hammering & Rock Breaking

The rock hammering method of boulder breaking is a process of hammering the boulder by either a hydraulic or pneumatic hammer until the boulder breaks. The hammer is usually mounted on a boom. The motor, hydraulic pump, and oil reservoir are usually located near the boom. Figure 14 shows a typical hammer installation.

The advantages of this method are continuous operation (minimal downtime for boulders), no need for explosives, safer environment for the operator, and the hammer can be used to clean grizzlies.

The major disadvantage of the rock hammering method is the initial capital cost of the hammer.

The breakers have developed into a third generation model which requires less maintenance than earlier models. A variety of breaker points are available in order to achieve optimum performance for different rock characteristics.

Rock breaker designs are of two basic types. One type utilizes high impact blows at low frequency while the other type produces a much lower impact blow delivered at a much higher frequency. Frequencies can range from 25 to 450 blows per minute with blow energies developing between 1,000 and 20,000 ft-lbs per blow.

stone crusher efficiency hydraulic rock hammer

A variety of breaker points are

By | 2017-07-24T12:46:38+00:00 July 24th, 2017|Categories: Crushing & Screening|Comments Off on Rock Hammering & Rock Breaking

Rock Boulder Blasting with Explosive

Boulders can be broken up using either explosives or mechanical methods which can be implemented in many ways. Handling boulders hung up in crushers is inherently inefficient for the overall operation, and the techniques in handling them each have their own advantages and disadvantages.

Table 4 shows a comparison of explosive boulder breaking techniques. When these methods are used it is important to make certain that the crusher feed is empty of rock that could transfer shock energy from the explosive detonation and damage the crusher. The table summarizes economic evaluations of some blasting methods on the basis of drilling need, and type and amount of explosives needed to break a cubic yard of rock. For each method, either dynamite or binary (two component explosives) can be used. The methods will be explained in detail, but it must be emphasized that cost figures shown in Table 4 cannot adequately include the cost for any increased accident potential that could result.

This section covers techniques found in use in mines and quarries or likely to be in use. A later section describes new technology that are not presently well enough developed for use for boulder breaking.

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By | 2017-07-24T12:34:51+00:00 July 24th, 2017|Categories: Crushing & Screening|Comments Off on Rock Boulder Blasting with Explosive

In-Situ Uranium Mining

Figure 5 displays the results of the uranium analysis as a function of time on one of the tests in which oxygen and hydrogen peroxide were used alternately. Except for the initial run with oxygen, the composition of the pregnant liquor over the duration of the extraction cycles were essentially the same whether oxygen or hydrogen peroxide were used as the oxidant. The first run is also fairly typical in that it gave high U3O8 concentrations with a substantially higher peak than did subsequent runs. From the data on these runs in Table 1, it can be seen that there was no obvious distinction between the average injection rate or extraction rate in this test when the oxidants were alternated. Some variation occurred from one cycle to the next but these swings are typical in a production field. They are often dependent on the particular phase of adjoining wells as well as the variations with time in the resistance of the well screen and the adjacent porous zones. Also, the variations in either average or maximum U3O8 content are not outside the typical changes from cycle to cycle obtained with a single oxidant.

Figures 6 and 7 illustrate two typical production

By | 2017-07-24T14:15:14+00:00 July 24th, 2017|Categories: Hydrometallurgy|Tags: |Comments Off on In-Situ Uranium Mining

Rock Boulder Exploding Techniques

Several products have come on the market in recent years that improve the safety of secondary blasting operations. The most significant of these are binary explosives, exploding bridgewire electric blasting caps, and nonelectric systems.

Binary Explosives

Binary explosives are two nonexplosive materials that become cap sensitive, high energy explosives when mixed. One part can be fertilizer grade ammonium nitrate, and the other nitromethane. Oftentimes they are available in plastic tubes or flexible foil pouches that can easily conform to the boulder surface. These explosives can replace stick explosives for mudcapping although they are more expensive.

Since binary explosives are not classified as explosives until mixed, their storage and handling is greatly simplified and less costly. They are also less sensitive to shock than dynamite and do not cause powder headaches for the user. As mentioned, the extra cost of the product is a primary disadvantage. Care must be taken when inserting the cap in the charge to assure detonation. It is best to insert a blasting cap only about 0.5 in.

Several binary explosives are available as shown in Table 5. Their properties and costs are compared with conventional explosives.

Exploding Bridgewire Caps

One disadvantage of electric blasting caps is their susceptibility

By | 2017-07-26T11:17:33+00:00 July 23rd, 2017|Categories: Crushing & Screening|Tags: |Comments Off on Rock Boulder Exploding Techniques

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