Bowl Classifiers

The bowl classifier incorporates a two-stage baffled-return separating action, and it consists of a straight classifier with the usual reciprocating rakes, upon which is superimposed at the lower end a shallow circular bowl with a revolving rake mechanism. The general construction of the Dorr Bowl Classifier is shown in Fig. 20.

The feed enters at the centre of the bowl, and, falling on to a baffle-plate placed at the level of the surface of the pulp, is directed radially outwards. In passing from the centre to the periphery the coarser particles settle and only the fines overflow into the annular launder provided for the purpose. The oversize, as it settles, is ploughed to the centre by the revolving rakes and discharged through a rectangular opening into the second stage or reciprocating rake compartment, where it is dragged up along the sloping bottom of the tank exactly as in a straight classifier.bowl_classifier

The movement of the rakes in the restricted space beneath the bowl is regulated to give enough agitation to throw the finer solids into suspension. The diluting water is added in the reciprocating rake compartment ; it flows back towards the bowl ….Read more

Hydraulic Classifiers

Hydraulic classifiers range from simple V-shaped launders with a multiplicity of shallow settling pockets for the discharge of as many roughly sized products to the more elaborate deep-pocket machines of the hindered- settling type, having specially designed construction plates and automatic discharge of spigot products.

Dorrco Sizer

In the eight-pocket machine, the pockets are separated by 3-ft.-high partitions and increase in cross-sectional area from 1 sq. ft. in the feed end to 3.12 sq. ft. in pocket 8. The size of hole and hole spacing in the constriction plates depend upon the size distribution of the feed and are designed individually for each installation, so that the hydraulic water required for each compartment will flow through the holes at a predetermined head loss. This hydraulic water is supplied from take-offs arranged along a common manifold, and the flow is controlled by individual valves. Windows are provided in each compartment for inspection of the teeter bed. The discharge mechanism is fully automatic, the spigot valves being operated by a modulating motor controlled by a pressure unit that, in turn, is actuated by the pulp density within the compartment. This eight-pocket unit operating on minus 14-mesh iron ore of average size distribution has a ….Read more

Screw-Spiral Classifier: Select, Size & Install

The size of mechanical classifier required for a particular job depends on the following factors:

  1. Tons of dry solids to be overflowed per 24 hours. This is simply a predetermined tonnage.
  2. Mesh size at which separation is to be made. The mesh size is determined by laboratory tests or is already known from previous experience.
  3. Density desired in the overflow. This is dependent upon subsequent treatment.
  4. Settling rate of solids, of the size at which separation is desired, in pulp of the particular density of the proposed installation. This is determined by laboratory settling tests.

Overflow Capacity of the Mechanical Classifier

If the settling rate has been determined by laboratory tests the classifier pool area required is obtained from the following formula:

Effective pool area, sq. ft. = Vol. overflowing, cu. ft. per min/Settling rate, ft. per min.

This is the best method of determining the required pool area. However, if settling tests have not been made and it is inconvenient to make tests, the following procedure, which has been proved to be entirely satisfactory, may be used.

Table I gives the overflow capacity, per sq. ft. of classifier pool, in tons of dry solids and in cu. ft. of pulp per 24 hours, ….Read more


Hydroclassifiers are solving the most difficult fine sizing and desliming problems by combining high metallurgical efficiency in a rugged, well- built machine to accurately fulfill the exacting conditions required. Accurate separations can now be made in the 100 mesh range and finer. This fine separation requires considerable classification area per ton as well as minimum agitation and accurate control.

New processes in the flotation, cyanidation, chemical, and industrial field are now opened up by this new machine. Definite applications include elimination of slime from breaker sludge in the anthracite field in ball mill classifier circuits where there is an extremely fine grind and slime separation is required in regrinding and desliming circuits, and in many leaching methods where a slime-free product is necessary.Hydro-Classifier

How a Hydroclassifier Works and Operate

The feed is brought into the center feed-well, and distributed in a quiet zone, the sand or coarser product settles evenly on the sloping bottom and the fine sized product overflows the circular rim into the launder. The slowly rotating spiral rakes continuously convey the settled material to the center cone where water is added under a perforated plate to displace the slimes from the granular solids before they are removed ….Read more

Flash Flotation with Closed Circuit Grinding

The reason why you need Flash Flotation in a Closed Grinding Circuit relates to “Recovering your mineral as soon as free” which has long been recognized in ore dressing practice. This not only applies to gravity treatment but also to flotation. For this application the Flash Flotation Cell was developed for use in the grinding circuit and has done a remarkable job in many plants.

Flash Flotation with Closed Circuit Grinding4 Options for Flash Flotation in a Closed Circuit Grinding Plant

A greater amount of granular higher grade concentrates can be produced and, in general, overall plant recovery is improved by reducing slime losses due to overgrinding and colliding of high specific gravity minerals.

Closed Circuit Grinding Flowsheets with Flash Flotation Embedded

Typical flowsheets are shown to indicate a few of the possible applications of Flash Cells in grinding circuits. In recent years the successful application of hydraulic cyclones, rubber lined pumps, and two stage grinding circuits have enhanced the feasibility of unit cell applications. Cyclones in particular have increased the flexibility of such applications by permitting positive and continuous gravity flow of unit cell tailings to subsequent treatment steps.

Closed Circuit Grinding FLOWSHEET #1

In this ….Read more

Grinding and Classification Circuit

Our EXAMPLE Grinding and Classification Circuit is designed to grind 500 tonnes of ore per day, operating 24 hours per day, with an availability of 95%.  This circuit will grind -5/8″ material from the Crushing Plant, classify the slurry in one of two cyclones, and pass 70% of the minus 200 mesh material to the mill feed Thickener Circuit at a rate of 22 mtph.
This section is intended to be read in conjunction with the Flowsheet and Piping and Instrument Diagrams.

The Grinding and Classification Circuit is designed to the following criteria:

F80 Feed Size 80% minus 7/16″ (11,000 microns)
P80 Product Size 70% minus 200 mesh (75 microns)
Ore’s Bond Work Index 17.7
Circulating Load 400%
Ball Mill Power 800 HPgrinding circuit ball mill

Detailed Process Description and Control: Crushed ore in the fine ore bin flows through a slot feeder onto a 30″ variable speed belt feeder. The
bin low level alarm on the mill control panel annunciator will inform the mill that there is a shortage of feed material. The belt feeder has level and
pullcord switches identical to the other three conveyors. In addition, the belt feeder is equipped with two speed switches; one at each pulley, in order to ….Read more

How to Improve Cyclone Separation

Good cyclone separation depends upon control of pressure drop, pulp density and apex size. The ‘pressure drop’ may vary but should not change rapidly, and is held at safe levels by keeping an adequate sump level. A falling sump level causes cavitation in the pump and reduction in feed rate; pressure drop in the cyclone falls and solids report increasingly to the overflow until the drop approaches zero and the entire slurry stream passes into the underflow. Additionally, while maintaining the required separation parameters, the pressure drop should always be minimised to minimise energy losses, thus reducing pump and cyclone wear. The maximum ‘pulp density’ is usually about 50% solids by weight; above that level small fluctuations in density will seriously affect separation. A cone-shaped discharge of 20°–30° reduced angle usually produces optimum conditions for separation. Cyclone control is best obtained by optimising the feed density. With consistent ore types the cyclone feed density is a good indicator of cyclone overflow sizing. A ropy cyclone underflow indicates a very high-density state with a risk of plugging the ‘apex’. If control cannot be exercised either a larger apex is needed, or the addition of another cyclone.

Striking an economic ….Read more

Solvent Extraction & Electrowinning (SX/EW) Plant Design

SX-EWCerro Verde began operations in April 1977, originally formed and operated by Minero Peru, as a state-run mining company. The electrowinning tankhouse was designed to produce 33,000 metric tonnes per year (mtpy) of copper cathode operating with current density of 184 amps per square meter (A/m2) and 88 percent (%) electrical current efficiency. In 1994 the mine was privatized and purchased by Cyprus Amax, which undertook an expansion project to expand cathode production to 48,000 tonnes per year using a current density of 250 A/m2 and 90% current efficiency. Cathode production surpassed this design by 1997 through innovative process optimization and increasing current density. Phelps Dodge Corporation purchased the property in 1999 and production continued to increase with current densities reaching 368 A/m2 in 2002.

This article discusses modifications to tankhouse electrolyte flows, tenors and temperatures, electrode geometry changes, cell modifications, smoothing agents, cycle times and operating practices which resulted in higher production levels while improving the copper cathode quality

The Cerro Verde mine is located in southwestern Peru, about 20 kilometers south of Arequipa at an elevation of 2700 meters. The mineral resource is a porphyritic sulfide deposit that had ….Read more

Hydrocyclone Rubber Liners

We sell Rubber Liners for Hydrocyclone:  You can buy parts like the main body liner, lower cone and Apex or Vortex.

Long lasting, good wear and better price VS life relationship than a Linatex types Brand.

Hydrocyclone Replacement Vortex Hydrocyclone Rubber Lower Cone Liner Hydrocyclone Apex Hydrocyclone Rubber Liners -Alternative to Linatex

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