博文

目前显示的是 七月, 2018的博文

Separation by Gravity

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In mineral processing plant , After liberation of all individual minerals in a rock or an ore feed, either by grinding or by natural size reduction ( iron ore processing a.o.) they can be separated individually. Depending on their behaviour, different technologies are applied. We  will cover the classical methods of separation as per below. This article describe the way of gravity separation. Separation by Gravity If there is a certain difference in density between two minerals or rock fractions they can be separated by using this difference. Separation by gravity covers two different methods. • Separation in water (Gravity concentration) • Separation in a heavy medium (Dense Media Separation, DMS) Separation in Water Separation by Jigs The jig operation consists of two actions. One is the effect of hindered settling meaning that a heavier particle will settle faster than a light particle. The other one is the separation process in an upward flow of wa

Ore washining and water treatment

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In mineralprocessing , Washing , mainly used in the enrichment process of industrial minerals, coal,aggregates, sand and gravel, normally with the products in solid form. (size = 1 mm and coarser). Log washers Single or double shaft log washers are used for washing of gravel. Contaminated material is fed at the trough bottom and is transported upwards by blades in abscrew pattern due to friction between the material. Effluent in slurry form leaves via an overflow weir. Wet screens Water spraying can be used to wash materials on a screen regardless of hole size in the screening media. If the hole size is 20 mm or less, water spraying increases the capacity (inversely proportional to the hole size). Aquamator separator The Aquamator is developed for efficient washing of waste material of lower densities like coal, wood etc. Used mainly for gravel, chippings and demolition rubble. The water and feed form a bed with a density high enough ( SG range1.2-1.6) enabling l

Size Control in Crushing and Grinding Circuits

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Crushing circuits - open screening • Screening ahead of a crusher avoids packing • Less wear in the crusher • Higher total capacity • The screening media is “controlling” the product in two dimensions. No “flaky shortcuts”. Crushing circuits - closed screening • The screens are lowering the capacity • Calibration of the product is improved • Better cubical shape • Higher reduction ratio Grinding circuits – screening • Used for “trapping critical sizes” in AG - SAG circuits (1) • Used for taking out size fractions from AG circuits for pebble grinding (1) • Used in circuits with heavy minerals – avoiding over grinding (fine screening) (2) • Screens being static (fixed cut point) are not too tolerant to changes in product size, causing variations in circulating loads. • Mechanical damage or clogging of screening media can disturb operation. Grinding circuits – classification • Classifiers being dynamic (floating c

Ore material size classification

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For size control of particles finer than 1 mm, we are moving out of the practical range of conventional screens. Classification is the process of separating particles by size into two or more products according to their behaviour in air or water (liquids). Classification methods • Wet classification with Hydrocyclones using separation by centrifugal force covering the size range of 100 – 10 micron (typical) • Wet classification with Spiral classifiers using separation by gravity covering the size range of 100- 1000 micron (typical) • Dry classification using separation by centrifugal force covering the range of 150 – 5 micron (typical). Wet classification – fundamentals If a particle has no interference from other particles it moves faster than a particle surrounded by other particles due to increased density and viscosity of the slurry. This is called free and hindered movement and is valid both for gravity and centrifugal classification. Hydrocyclone Centrifug

Ore material size control

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In beneficiation plant , With size control we understand the process of separating solids into two or more products on basis of their size. This can be done dry or wet. neither crushers nor grinding mills are too precise in their size reduction job and a lot of size fractions are misplaced. By using optimum size control the result can be improved both regarding capacity, size and particle shape. Size Control by Duties To prevent undersize in the feed from blocking the next size reduction stage(scalping) To prevent oversize from moving into the next size reduction or operation stage(circuit sizing) To prepare a sized product (product sizing) Size Control by Methods In mineral processing   practices we have two methods dominating size control processes: -Screening using a geometrical pattern for size control. -Classification using particle motion for size control. Screens Performance of screens will fall back on three main parameters: Motion – Inclina

Grinding vs Enrichment and Upgrading

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In mineral processing plant , In the size reduction stages of grinding we are also creating the conditions for the following process stages of enrichment and upgrading. From the picture below we can see the effect of “under- and over grinding” The lost performance in separation, sedimentation and dewatering due to “misgrinding” represents a major problem for many operations, eroding the process economy. sinonine can also provide  sand washing plant  epc.   Sinoninetechnology team