brazil high quality environmental copper mine circular vibrating screen manufacturer

china customized natural rubber tumbler vibrating screen suppliers & manufacturers - factory direct wholesale - yinxing

china customized natural rubber tumbler vibrating screen suppliers & manufacturers - factory direct wholesale - yinxing

Product brief introduction Working Principle Features 1.Up to 5 times output per unit area. 2.Sieving efficiency is as high as 90% -95%. 3.The acceleration is 4.5 times lower than vibrating sieve. 4.Sieving parts increases the life expectancy and reduces maintenance. 5.Up to 5 times output per...

Why Choose Yinxing? 1) International high quality certification product chain 2) Manufacturer, more reasonable price 3) Solid technical support and after-sales service 4) Uphold the principle of Customer Supreme 5) Exports to more than 20 countries and regions, good customers feedback 6) One-stop service, customized exclusive project feasibility report.

dewatering screen machine manufacturer - gaofu

dewatering screen machine manufacturer - gaofu

Because of environmental protection requirements and customers' needs to reduce costs, Gaofu has developed a dewatering screen. As a manufacturer with 38 years of experience in screening, Gaofu pays more attention to the improvement of customer quality and efficiency. This dewatering screen meets the market demand.

Compared with the traditional process, Gaofu companys new-type dry-line dewatering process has the advantages of low investment, simple process and small area which is convenient for the system process layout.

The dewatering screen features high wear-resistant screen plates with a long lifetime, modular assembly design, easy replacement, and low cost savings. Also screen mesh sizes can be selected according to requirements.

Dewatering screen is composed of mainly the screen box, exciter, support system and motor. Two counter-rotating vibration motors produce linear motion at an angle to the screen surface. The centrifugal force generated by the two eccentric masses is superposed along the vibration direction and reversely counteracted, thereby forming a single vibration force along the vibration direction and making the screen box reciprocating linear motion.

Dewatering screen, also known as high-frequency dewatering screen, changes the water surface tension of pulp through the exciting force. Thee washed sand is fed to the steep, downwardly inclined surface of the sand dewatering screen, so as to achieve rapid drainage. The dewatering screen is mainly used for dewatering tailings in the mineral processing industry, coal slurry dehydration of coal preparation plant, washed quartz sand dewatering and ceramic slurry dehydration, and wet and dry classification, dehydration, removal and mud removal of medium and fine granular materials in industrial sectors such as electric power, sugar making and salt making.

Dewatering screenadoptdual-electrode self-synchronization technology, universal eccentric block, adjustable amplitude vibrator. The machine is combined mainly by the screen box, exciter, support system and motor. The two mutually independent vibrators are respectively driven by the tape coupling to do synchronous reverse operation. The centrifugal force generated by two eccentric masses is superposedalong the vibration direction and reversely counteracted, thereby forming a single vibrationforcealong the vibration direction, making the screen box reciprocating linear motion.

Dewatering screen, also known as high-frequency dewatering screen, changingthe water surface tension of pulpthrough the exciting force, pulp water through the screen to become the undersize material, and fine material is blocked by the screen to form the filter layer by the vibration of the forward movement of discharge. Dewatering screen is mainly used for detailings dewateringin the mineral processing industry, coal slurrydehydration of coal preparation plant, washed quartz sanddewatering and ceramic slurrydehydration, and wet and dry classification, dehydration, removal and mud removalof medium and fine granular materials in industrial sectors such as electric power, sugar making and salt making.

Gaofu machinery is made for each tailings dry process technology are efficient and energy-efficient minimum operating costs of the process. Drying of the slag after filling the pit, field, dam, manufacturing building materials, the filtrate to achieve the requirements of recycling ...

Washing sand dewater screen install a special sprinkler system, the feed for multi-channel spray washing, so that the soil from the sand completely separated to ensure the smoothness of sand. The sand washing system can effectively reduce the amount of fine sand loss, so that it is controlled within 5% -10% ...

Gaofu potash feldspar dewatering screen has less investment and energy consumption than filter press, which is convenient in operation and has a better effect than spiral classifier. It is the first choice of potash feldspar mineral separation and dehydration. Potash feldspar need to be graded after milling. The large particles back to the ball milling, ...

Sludge dewatering system includes slurry pumpdewater screen Cyclone and power supply system. Single set of systems can achieve grading leachingdehydrationit can effectively reduce investment costsoperating costs. ...

mining technology | mining news and views updated daily - mining news and in-depth feature articles on the latest mining company deals and projects covering trends in mineral exploration with up to date data on the most mined metal and mineral commodities

mining technology | mining news and views updated daily - mining news and in-depth feature articles on the latest mining company deals and projects covering trends in mineral exploration with up to date data on the most mined metal and mineral commodities

We aggregated thousands of records from GlobalData's proprietary jobs, deals, patents and company filings databases to identify the top companies in the area of artificial intelligence in the mining sector.

We aggregated thousands of records from GlobalData's proprietary jobs, deals, patents and company filings databases to identify the top companies in the area of artificial intelligence in the mining sector.

With Australia reportedly mulling a net-zero emissions target that could bring its climate goals in line with other countries while also having a major effect on the countrys mining industry, our staff writers each identify one policy they would enact to equip Australias mining sector for the challenges ahead.

With Australia reportedly mulling a net-zero emissions target that could bring its climate goals in line with other countries while also having a major effect on the countrys mining industry, our staff writers each identify one policy they would enact to equip Australias mining sector for the challenges ahead.

screens offer new era in process efficiency | e & mj

screens offer new era in process efficiency | e & mj

While vibratory screens have been a mainstay in mineral processing for more than a century, recent technological advances surrounding drives, wear parts and media are creating new possibilities for their application. From replacing hydrocyclones in classification duties and dewatering tailings to preconcentration, these machines are proving flexible and reliable tools as mines look to drive down their processing costs and increase their output, while minding their resource consumption and operational footprint.

Digital solutions have also proven invaluable over the past 12 months, allowing operators to monitor and control screens remotely, predict potential issues and schedule maintenance activities more efficiently.

As mines explore this new potential, vendors have been working to boost their manufacturing and service capabilities, add new solutions and better serve their client bases. E&MJ spoke to eight equipment providers about the trends they are seeing across the industry and how they are responding.

When this is coupled with machines using high-frequency and low-amplitude vibration, the results are industry leading conveyance and flux rates, David Perkins, director of technical sales for the Mining and Industrial Division of Derrick Corp., said. Derrick equipment is capable of processing more tons of material per area than any other manufacturer. Installation costs are often lower for the client due to a smaller plant footprint, lower total weight and negligible dynamic loads to the supporting structures.

Derrick equipment can be found on six continents in almost every commodity, from alumina to zirconia. Top markets include iron ore, gold, lead/zinc and silica. Derrick screens are often used to replace hydrocyclones in grinding circuits where clients benefit from increased product recovery and higher capacities that are beneficial to the environmental, social and corporate governance (ESG) impacts of a mining and processing operation.

We are seeing trends toward more environmentally-friendly processing. Clients are looking for ways to be more sustainable through process equipment that offers increases in capacity and recovery, Perkins said. In some cases, ESG is as much of a driver as cost to produce.

Derricks SuperStack technology features up to eight decks, each equipped with Dereks patented polyurethane panels. The combination of these two technologies allows the machines to replace hydrocyclones in grinding circuits essentially performing the role of classifiers which they do much more efficiently and cost effectively. The result is that the operation can produce more product using the same amount of energy or less.

In fine grinding circuits, our SuperStack technology can take separation efficiency from 50%-60% up to 85%-95%, which can increase the total capacity of a grinding circuit by 20%-25%, Perkins explained. For instance, if a mine is running 100 tons per hour, now they can run 125 tons per hour with the same amount of power. At the same time, the recirculating load will decrease from 300% to 100% so the cyclone feed pump, which is now technically a screen feed pump, can be half the size and again, consumes half the electrical power. This drives down the overall cost per ton of ore processed.

Screens separate material based on particle size, whereas hydrocyclones separate based on density. In some metal mines, theres a big difference in specific gravity between the ore and gangue minerals but, in others, iron ore for example, both fine iron ore and coarse silica have similar densities so both will report to the overflow. Its very difficult to separate the two using hydrocyclones.

Screening can be a game changer for these operations, Perkins said. Screens offer higher recovery, send less material to tailings and increase profitability. Most of our projects have payback periods of two to three months.

During the past 12 months, Derrick has been working to improve its customer relations and support with a wholly owned and operated international sales organization with local offices in South Africa, Canada, UAE, Indonesia and the USA. Staff are being added to support these offices and also at the companys manufacturing facility in Buffalo, New York.

We recently completed delivery of 24 SuperStack screens to a Metalloinvest Management Co. LLC-Mikhailovsky GOK operation in Russia, as well as an iron ore mine in Brazil and a phosphate mine in South Africa, Perkins added.

Vales Gelado project, part of the Carajs mining complex in the Par state of Brazil, selected Derricks SuperStack technology to develop an innovative tailings handling method and create a high-value green product. The new process lowers emissions in mining and steelmaking, producing high-quality iron ore at a lower cost than other Carajs operations.

Vale selected a single eight-deck SuperStack for Gelados fine screening requirements. This is fitted with 150 micron (m) aperture high-open-area, wear- resistant, non-blinding Polyweb screen panels to process more than 200 dry metric tons per hour (dmt/h) of iron ore.

That is more than twice the capacity of the previous industry-leading technology in a similar footprint, Perkins explained. The patented Front-To-Back tensioning system reduces screen maintenance time by up to 75% compared to previous best-in-class screen tensioning systems.

The new process has allowed Gelado to turn the cost and risk associated with tailings management into a positive cash flow stream, and the project is expected to recover 10 million metric tons per year (mt/y) of high-grade ore from the Gelado tailings dam over a 10-year period.

There are some overlaps into construction and aggregates, but our products are designed specifically for the 24/7 nature of high-capacity mining operations where reliability and availability are a top priority, said global product director, Eddie McKerr.

We design and manufacture screening technology in accordance with a mines specific equipment, functions and operating parameters, and offer customized support and installation tailored around any unique characteristics.

Our screen media product family, which comes in many different materials, is varied and customizable to diverse machines and use cases. We work with customers to determine the job the screen media will be doing before selecting the material. We then provide on-site technical assistance during installation, custom repairs at the mine or quarry, process optimization, specialty product development, a screen surfaces audit, and screen system and component installation.

FLSmidth recently launched the Screen Motion Analyzer (SMAv2). The lightweight, portable unit is temporarily affixed to vibrating screens using magnets and records the vibration of the screen in three directions (horizontal, vertical and lateral) simultaneously. The device then calculates and displays information on screen operating frequency, vibrating stroke and lateral displacement (Pk-Pk).

The data is automatically transmitted via wireless Bluetooth to a user-friendly app (on any Android or iOS device), which displays the data in a way that is easy to interpret, with no specialist training required. The data and reports can be saved for records, further analysis and/or sent to an FLSmidth machine analyst for an expert opinion.

Vibration analysis provides detailed information about the performance of each machine and shines a spotlight on potential problems that could reduce their life. The SMAv2 provides an instant snapshot of machines performance, allowing mines to adopt a predictive maintenance approach, reduce their downtime and cut costs.

The SMA is ideal for on-the-run monitoring of screens between major shutdowns, McKerr said. We are also working on optimized wear packages with products, such as our FerroCer Impact Wear Panels and screen media with enhanced wear life, all of which can enhance the user experience and reduce equipment downtime.

FLSmidth has also been working to improve its vibrating screen protection guards. The guards new homogeneous molded design eliminates fabricated joints to reduce stress points and increase their strength.

McKerr explained: We have developed a product using improved material, which makes them lighter weight. The smarter design makes removal and installation easier, and longer life is delivered due to the material chosen for manufacture and subsequent corrosion resistance.

General Kinematics is known as the leader in Two-Mass vibratory technology for screens. Its a game changer for the industry, Derek Kerkera, market director for mining at General Kinematics, explained. We have been doing two-mass designs since our company began in 1960.

Two-Mass refers to a style of vibratory equipment where one mass (the exciter, i.e., the drive) is used to mobilize a second mass (the trough or body). The exciter mass is the total weight of the vibratory motor(s) plus the steel structure designed proportionally to the total trough weight in addition to the amount of the material load. The exciter mass is connected to the trough structure through a network of springs distributed evenly between the two. This creates a sub-resonant system that responds to changes in load without dampening performance and efficiency.

The difference between Two-Mass and the industry standard of brute force is simple, Kerkera said. With brute force technology, the driving force is attached directly to the structure that carries the material. This style requires constant high horsepower to operate and does not provide a linear stroke down the length of the unit.

A Two-Mass machine provides a linear stroke down the entire length of the unit, and the design reacts in a positive manner (stroke will increase) to material loading, whereas the brute force reacts in a negative manner (stroke will decrease). A Two-Mass machine can also carry a heavier burden and a higher capacity than the same size brute force machine. Two-Mass machines are able to process up to 40% more material with greater efficiency while using less power.

Typically, we see brute force machines failing structurally between six months and two years of operation, while our Two-Mass designs will operate for five to eight years before needing refreshing, said Kerkera.

The company made two acquisitions in early 2021: Cyrus and Foundry Equipment Co. were purchased to increase its capability with turnkey projects worldwide and also to increase its presence in Europe and South Africa.

Many clients wish to increase their capacities at the moment in line with demand and commodity prices, so weve been testing more material in our lab, Kerkera explained. Most comminution circuits run well below their design tonnage due to brute force screens that are unable to operate reliably at circuit design tonnages and required efficiency.

General Kinematics is currently finalizing an STM S3685 single-deck screen which is destined for Copper Mountain in British Columbia later this year. The unit will be delivered via a brief stopover at MINExpo where it will be the star of the General Kinematics booth.

It will be their second unit from us, Kerkera said. This model features a new patented spring design called the Duro spring. Typically, a spring is bolted by attaching the pig tail of the spring to a plate putting the mounting hardware in tension. The Duro spring doesnt have a pig tail, it has a swaged end to the spring which put the mounting in shear. This is a much better condition and removes the issues sometimes seen from erosion. It also allows a higher stroke level with less stress on the spring.

Kwatani has 46 years of experience supplying more than 16,000 customized vibrating units into 47 countries worldwide. It designs and manufactures a range of linear-motion vibrating screens and feeders which are driven by in-house manufactured exciter gearboxes or unbalanced motors. Kwatani announced on May 7, that its to be acquired by Sandvik Rock Processing Solutions. The transaction is expected to close in Q4 2021 subject to regulatory approvals.

Kwatani offers a complete screening application portfolio from ROM equipment such as grizzly and scalping screens (the largest processes 7,000 mt/h of iron ore), to high-capacity multi-slope screens, desliming, drain and rinse, dewatering, and sizing screens up to 4.8 meters wide, including a range of brute force feeders.

Aside from customizing the deck layout and footprint for our machines, we customize each screens parameters including the drive angle, decline, stroke and acceleration to achieve the optimal design, explained Schoepflin. For example, in certain applications Kwatanis vibrating screens incorporate a higher stroke and G-force which can lead to increased throughput and efficiency.

Kwatani is currently manufacturing screens for gold mines in Quebec and Ontario; a coal mine in Siberia; chrome and diamond mines in Russia; diamond mines in the Republic of Congo, Angola, Lesotho, Botswana and South Africa; a mineral sands operation in Madagascar; and copper mines in Zambia and the DRC among others.

Kwatani also custom designed a vibrating screen for a gold mine to handle 1,500 mt/h of solids and 2,000 m3/h of slurry with a screening efficiency of +95% at a desired cut point of 0.5 mm. This 3-m-wide horizontal vibrating screen significantly increased the total plant capacity while ensuring 0% slurry carry over at the screen discharge.

In a manganese application, Kwatani supplied a 2.4-m-wide vibrating screen equipped with 80-mm-thick rubber screen panels. Used to scalp 1,200 mt/h of ROM material, this screen easily processes material with lump sizes of up to 300 mm. It has circular apertures on the top deck to minimize pegging of elongated particles. The Kwatani design managed to double the throughout achieved by the previously installed screens.

On one hand, customers focus on reducing their capital expenditure, while on the other they demand reduced lifecycle costs which include a reduction in maintenance costs, avoiding unplanned stoppages, increasing production tonnages and efficiency, he explained. Kwatani offers a competitively priced product paired with an optimal lifecycle and service offering. We are able to offer competitive prices for our equipment due to optimized production processes, currency hedging and our location in South Africa.

For brownfield projects/competitor replacements, we have a dedicated team to take measurements on site and so far, Kwatani has always optimized the efficiency and performance of the screen on the same plant footprint.

Thanks to various technological advances, screens are proving flexible and ever more reliable tools for mines looking to drive down their processing costs and boost their output. (Photo: General Kinematics)

Multotec manufactures a range of mineral processing screens and media for mining operations across the globe. Roy Roche, vice president of screening Media at Multotec, spoke about the companys current focus areas.

What sets Multotec apart is that we use a wide range of construction materials in our screen media, he explained. We control the manufacturing process ourselves and utilize an iterative improvement process to extract longer term benefits for our customers. We combine this with deck map technology, wear life indicators and monitoring capabilities that further enhance their performance capability.

Significant expansion is currently under way in China, with the recent commissioning of a new 3,000-m2 manufacturing facility in Beichen, Roche said. We are also expanding in Chile with the addition of another factory to significantly increase our manufacturing capability in South America. And we are expanding both our service and manufacturing capability at our Belo Horizonte facility in Brazil.

Geographically, we are focusing on Southern hemisphere mining jurisdictions in conjunction with other markets like China, Russia and the CIS, and Canada. Bulk commodities like coal and iron ore make up a big chunk of our business along with base metals (copper, chrome, manganese, cobalt, nickel, etc.), precious metals and diamonds.

The new range of MBV screen media has been developed to improve the screening efficiency of fine, damp material without the addition of water, he said. The panels comprise a thin flexible membrane that allows screening at high G-forces. The product has been found to be particularly effective with sticky ores with a high clay content.

Multotecs South African engineers, in conjunction with Multotec in Australia, have also developed a range of hard-wearing impact panels for the iron-ore industry. The panels use a combination of alumina ceramic or Hardox steel inserts in combination with rubber to counter wear at the feed end of vibrating screens. Customers have reported the wear life of these Ceradox and Hardox panels to be three to five times that of conventional rubber impact panels.

We also developed a range of fire-retardant rubber screen panels that comply to the stringent safety standards set by some of the major iron-ore producers in Australia. These drastically reduce the fire risks associated with rubber products, Fouche added.

Stainless steel wedge wire has long been the standard material for the manufacturing of interstage cylinders for carbon-in-pulp and carbon-in-leach sections in gold plants. Multotec has developed a new interstage cylindrical screen using a polyurethane screen surface. This is currently undergoing testing at a number of South African gold plants. Results to date indicate that the wear life will be superior to wedge wire and that the product could provide a viable alternative to conventional wedge wire cylinders.

Multotec receives frequent inquiries to screen material at finer apertures. The bottom range for separation by screening has traditionally been in the region of 300 microns, but today, customers are asking for niche products that can screen at 100 microns.

Roche added: Another major trend were seeing now is remote monitoring of equipment in-situ, and the ability to predict failure patterns along with consistent product performance. Customers want products to meet predictable lifecycles so that they can improve and plan maintenance schedules. This is guiding our R&D endeavors where we are working with sensor systems to transmit relevant and coherent data related to specific product performance. This is aimed at eradicating catastrophic in-situ failures, unplanned maintenance and facilitating report backs on inefficient operating states. Artificial intelligence will play a significant role in these systems.

Frank Harris, director of mining sales, said, We focus on reliability and process improvement and we are the best at it. Polydeck is fortunate to have the most talented engineers in the mineral processing field, and we are led by ownership that has the vision and drive to be the best screening resource in the mining industry.

The company recently expanded its manufacturing operations in Spartanburg, South Carolina and, in April, was named winner of the South Carolina Chamber of Commerce 2020 Safety Award Winner for Workplace Safety.

Our team works closely with mining operations to ensure that they realize the benefits they expect, Harris said. Any product can be misapplied. Our mission is to ensure clients realize the value promised by helping them apply the right solution.

Polydeck recently helped Barricks Golden Sunlight operation in Montana to improve the throughput of its screens and reduce downtime. The mine was using heavy gauge wire cloth on its secondary scalping screen and experiencing buildup problems. The excessive travel rate and lack of bed depth were also causing issues. The three- to four-week average wear life was poor relative to other plants, and so the Polydeck team suggested switching the wire panels for its Rubberdex screen media.

Earlier this year, Polydeck released two new lines of ceramic and magnetic liners. The Magnetic Liners are designed with a combined holding force of up to 600 lb. Magnets are molded into the liner to maximize the surface holding force. The design also features molded 1-in. spaced cut lines to make in-field modifications easy for any installation.

Constructed of high-quality Armadex synthetic rubber, the modular Ceramic Liners provide long wear-life with high abrasion resistance and reduced noise levels, for lower maintenance costs and improved safety. Polydeck can mold the liners with different durometers to match any application.

Like many other manufacturers, Polydeck has jumped headfirst into the world of online training and education over the past 12 months, providing specialized training courses to help customers overcome COVID-related travel restrictions.

These help them continue to improve screening processes at a time when we cant be on site as frequently, or with as many people, Trey Rollins, director of marketing and inside sales, explained. Additionally, Polydeck has created informative webinars on topics most requested by customers as a way to stay in front of customers and potential customers. The increased willingness to utilize technology has also been a driving factor in the R&D space. We are fleshing out some ground-breaking concepts that will help solve huge problems for our customers.

We will be launching a new product category and providing a sneak peak of a new product line that will launch in early 2022 at MINExpo in September, he added. Both provide longer life, reduced wear and cost savings.

TEMA ISENMANN manufactures a range of open-cast and injection molded polyurethane screen panels, as well as patented magnetic liners and panels at its base in Lexington, Kentucky. It primarily supplies the North American mining and aggregate markets including the USA, Canada and Mexico using direct sales personnel and a network of dealers.

We have recently installed a five-axis CNC milling machine to increase the capacity for manufacturing our own tooling in house, and we have also increased our manufacturing capability substantially by automating parts of the plant, explained Anthony Yell, manager of TEMA ISENMANNs Mining Division.

Our open-cast polyurethane products have extremely good abrasion and impact-resistant properties, so for aggressive applications we tend to use open-cast polyurethane that will generally improve life by at least twice that of injection-molded panels.

There are lots of options available in different durometers from 60 to 90 shore A. In addition, we manufacture a range of dual durometer panels where we combine a soft 60 shore polyurethane top layer with a harder base in different colors. This not only improves certain screening applications, but the different colors work as a wear indicator when you wear through the top blue layer and expose the bottom yellow layer, its time to replace the panels. This versatile range of materials and panel sizes allows us to manufacture panels to suit most applications.

Since we are part of an international group of companies involved in the mining industry [that includes Steinhaus GmbH; Isenmann Siebe GmbH; Tema Group and Multotec Group], we also have access to numerous other screen media and materials, added Yell. These include compression molded and injection molded rubber panels, and hybrid Poly-Wedge panels that have a combination of stainless-steel wedge wire mats fastened to a polyurethane frame. This means they are consistent with the modular concept of 1- x 1-ft, 1- x 2-ft and 2- x 2-ft panel sizes.

TEMA ISENMANN also offers a range of TeePee high open-area, 3D panels that typically have double the open area of conventional flat panels, which results in double the drain rates. These can be used to increase the dewatering capacity of existing dewatering screens or allow the client to install smaller dewatering screens.

We regularly assist in checking screening sizing too, especially when clients want to convert from say woven wire to polyurethane to ensure they still have sufficient screening capacity available, added Yell. We make use of programs such as AggFlow to check mass balances, screening area and screening efficiencies.

Yell explained: With regard to new products, we are continuously growing and improving our range of apertures in both open-cast and injection molded panels. Our range of WS2.10 patented magnetic panels assist clients with reduced maintenance down time, especially on second and third decks where panels are notoriously difficult to replace due to space constraints. They are quick to remove and replace safely with minimal tooling.

Yell said the WS2.10 magnetic liners are proving exceptional in reducing downtime and, as there is no bolting required, there is no need for cutting and grinding equipment, which improves the safety of installation and removal. Another benefit is that plants can now standardize liners as they no longer need to keep left and right-hand versions, reducing inventory and costs.

The Saddle Top Rail System that has proven itself over the last 15 years in Africa and Australia, will be launched at MINExpo for the North American market and is fully compatible with existing runner systems.

It has proven to be far superior to most runner systems in the market not only because it extends runner life and is quick and easy to replace, but it supports the internal frame of the screen panels properly, said Yell. The polyurethane-polyurethane interface extends the panel life as well.

Our new magnetic-backed stroke gauges will be available free of charge to delegates, added Yell. These are really useful devices for checking whether a vibrating screen is operating to manufacturer specifications. There are a couple of other things we have up our sleeve too, but we dont want to give the game away at this time.

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ore, rock & aggregate screening (complete guide)

ore, rock & aggregate screening (complete guide)

A simple definition of a screen is a machine with surface(s) used to classify materials by size. Screening is defined as The mechanical process which accomplishes a division of particles on the basis of size and their acceptance or rejection by a screening surface.

Knowledge of screening comes mainly from experience. However, through experiment, test facilities and compilation of field data, reliable criteria have been developed by screen manufacturers. This factual data is now tabulated for use in selecting the type and size of screen best suited for the job.

The most common application of a vibrating screen is to separate an unconfined conglomerate of materials into different size fractions. Other popular uses of screens are scalping, washing, dewatering and dedusting. A review of the duty is essential to know the type of screen to recommend. When this is established, the capacity chart is then used to determine the size of unit required.

Nordberg-Lokomo supplies different types of screens, each designed for a specific range of duty. Occasionally there is a choice between the types we offer. In these cases when there is doubt, you can rely on Nordberg-Lokomo experience to help you make the selection.

COARSE FRACTION Particles which pass over the screen deck, FINE FRACTION Particles which pass through the screen deck. SEPARATION SIZE/ SPLIT SIZE Particle size at which feed separates into two products (coarse fraction and fine fraction). OVERSIZE Material larger than the hole size. UNDERSIZE Material smaller than the hole size. HALF SIZE Material smaller than half of the hole size. SCREENING CAPACITY (Q)Amount of material passing through the screen deck in tonnes/hour FEEDING CAPACITY Amount of material fed to the screen deck in tonnes/hour EFFICIENCY OF SCREENING (EFFICIENCY OF UNDERSIZE RECOVERY)Amount of material smaller than the hole size in undersize compared to the total amount of material smaller than the hole size in the feed.

The particle distribution of the feed has an essential impact on purity. See three examples in figure 1. In each one of them the efficiency is 90 %, but the undersize proportion of the coarse fraction varies (3.2 %, 9.1 %, 23 %).

Factors effecting the screening can roughly be divided into three groups: characteristics of material (B, C, F, K, L) characteristics of screen (D, E, AF) characteristics of screening element (A, G, H, J)

[t/h] (passing through) A = Nominal capacity [(m/h)/m] (passing through) B = Oversize factor C = Halfsize factor D = Deck location factor E = Wet screening factor F = Material weight [t/m] (bulk density) G = Efficiency factor H = Shape factor for mesh holes J = Factor for proportion of holes in the mesh K = Factor for crushed stone and gravel L = Factor for humidity content AF = Effective screening area [m]

The factors are obtained from diagrams based on relationships observed empirically. Since these factors are known, it is consequently possible to calculate the specific capacity of the screen in tons/h per square meter.

The amount of oversize describes the amount of the particles of the limit size. Particles which are considerably larger than the hole do not make screening difficult. Large stones push stones of limit size through the screening element.

The quantity of the half size is used to inform / present the quantity of the fine material. Material smaller than half the hole size passes through the screening element very easily. If a feed contains a lot of fine material, it can be fed in large quantities onto a screen. If there is little fine material the screening capacity falls. This is due to the fact that there are a lot of particles of limit/critical size. The throughput of particles of limit size (0.5 1.0 x hole) is very poor.

Flaky (thickness is small, relative to the other two dimensions) and elongated (length is larger than other two dimensions) stones are the most difficult to screen. They pass over the screen deck laying on their widest side. At worst they become wedged in holes and thus block the whole screen deck.

When the humidity is under 3 % it has no significant importance. The problems start at 4 5 %. At 9 30 % screening is very difficult. When there is more water the screening gets easier, and it is close to separation of water screening.

Stroke length, rotation speed, stroke angle, and screen inclination form together parameters which affect the operation of the screen. These fundamental factors have to be in proportion to each other. Stroke length and material amplitude have an effect on:

how the holes of the element stay unblocked. If the stroke length is too small also the material amplitude stays too small and the element gets blocked. The problem arises when the hole size is large (50 mm or more).

Acceleration of the screen box can be calculated by the stroke and rotation speed. When stroke angle and inclination are taken into the calculation, the vertical acceleration can be found. Vertical acceleration has an effect on the screening efficiency and the rate of travel.

Acceleration should be 4.5-5.5 x G (G=9.81m/s) with horizontal screens to reach a good screening result. To avoid structural damage for the screening unit, no acceleration greater than 6-7 times G are allowed.

Stroke angle has an effect on the material amplitude and the rate of travel. The most suitable stroke angle for horizontal screens is 55-60 degrees. Too upright a position can reduce the rate of travel. Horizontal stroke angle can improve the rate of travel but reduce screening efficiency. It also increases the wear rate of the mesh.

Speed of travel can be increased by inclining the screening surface. If the surface is greatly inclined, the stroke must be short to prevent material sliding over the mesh too quickly. Inclination of the surface can keep the mesh holes open more easily.

The bed of material may not exceed a height more than 3-5 times the size of the mesh hole on the discharge side of the screening surface. A higher bed of material will reduce the screening efficiency. Feeding capacity for each mesh size depends on the width of the screen. To get efficient screening results the depth of material bed must be at least 2 times the mesh hole diameter on the end side of the surface. Then volume of oversize will determine the width of the screen.

The depth of material bed should be within allowable limits on the beginning and the end of the surface when choosing the screen.Screening area is not theonly dominant parameter while choosing the screen. In practice the length is 2- 3 times the width.

A deck factor should be used when calculating lower decks in muitideck screens. In lower decks the feed drops not only at the beginning of the deck, but also later in the direction of the flow. That is why material close to separation size will not be screened out.

Effective screening area is the area where material can drop down through the surface. Effective surface area is about 0.7-0.9 times the whole area. The whole area is determined by the inside parameters of the screening unit: length times width.

Figure 3. Schematic diagram showing how the screening effect varies along the screen deck. Stratification takes place within zone 1, screening of fine undersize particles (75% of the size of the screen apertures) takes place within zone 2 and screening of critical undersize particles, i.e. particles of a size close to the size of the screen apertures, takes place within zone 3.

The amount of loading influences screening efficiency. In practice it is impossible to reach 100% efficiency. Maximum efficiency is about 95%. In most of the cases 90% is achieved and the screen can be said to be under 100% loading.

The greater the open area of the mesh, the more effective is the throughput. When determining the open area of the mesh, the diameter of the wire between holes in different meshes differs, and has to be taken into consideration.

The type of the mesh will have an effect on screening efficiency. The most significant difference will be in special screening cases. For example while screening elongated material, mesh should be of the vibrating type (rubber or harpmesh)

By scalping it is meant screening of coarse material in order to remove the undersize, typically before a primary crusher. Because of the coarse feed the top deck, which may be the only one, is often of a grizzly type. i.e. grizzly bars as opposed to mesh. This type of screening calls for a robust construction whilst there is no requirement for screening efficiency.

Leaving out the ancient trommel screens, stationary grids, and similar types, the following means are used to make the screen vibrate. All screens today are vibrated by various methods to pass the undersize through the apertures of the screen mesh or grizzly bars.

By freely vibrating screens one means screens that are supported on springs, and the box is vibrated by a vibrating mechanism (also called an exciter) which vibrates the screen box in various ways, depending on the type of vibrating unit.

Screens with a circular motion are the most common type. The vibration is circular because of a single eccentric shaft mechanism. This movement would not move the material forward, unless the screen is inclined in the direction of the material flow. This in turn means that the screening efficiency is not quite as good as a horizontal screen. The capacity as such is often higher as this screen is able to transport the material more quickly. The higher the inclination, the greater the transport ability. Inclination is typically 12 20. The inclination also helps to prevent pegging.

The depth of this material layer is more critical with a circular motion screen than with a horizontal screen. The inclination reduces screening efficiency. This type of screen may be used for almost any application. They are also cheaper to produce.

The vibration of this type screen is created by two eccentric shafts, rotating in opposite directions. This gives the box a linear motion. The stroke angle would depend on the relation of the eccentric weights of the two shafts to each other. Because of the linear stroke the material is moved in the direction of the stroke and the screen may be installed horizontally. That is why they are often called horizontal screens. The inclination would be typically 0 5.

The horizontal screen gives high screening efficiency, and they are often used for final and fine screening. Another advantage over inclined screens is their lower profile and therefore, horizontal screens mean lower structures and buildings, and shorter conveyors.

Elliptical motion can be achieved by various means. One method is by using three eccentric shafts, two of which would create the long axis and the third, the short one. These screens are used in special applications where the aim is to gain advantages of both circular and linear motion screens. It is a compromise however, there would also be a measure of disadvantages. These screens are typically installed at an 0 5 angle.

The eccentric shaft(s) of this screen type are connected both to the screen box and the foundation. The two shaft type would give a circular motion whilst the single shaft type would give this near the vibrating unit, and differ with the loading, depending on the action at each end.

These screens are used mainly for screening coarse material. The screens become heavy, and the dynamic forces which the foundation has to absorb, are a disadvantage. Brute force screens are installed 12 20 inclined.

The vibration of this type of screen is created by the resonance between the under-frame and the screen box or decks, and because of the resonance little energy is needed to vibrate the box. These screens are always installed horizontally.

The advantage of this type is the high efficiency as the screen can be very long, and therefore are mainly used for fine screening. They also have a low profile which can be advantageous. However they have very heavy and expensive structures.

Sizers are generally small and equipped with multi decks to assist screening. The products of two or more decks are often blended in the chute work of the screen. They have very high capacity because of the inclination. The apertures of the meshes need to be considerably larger than the cut, and thus affect the efficiency. This is compensated for by the blending. The advantage of this type is that it can be used for difficult material with less blinding than with other types.

The steep angle at the feed end gives the material a high velocity, some 3 4 m/s. Later the angle levels out and slows down the material to 1 1.5 m/s in the middle and 0.5 0.8 m/s at the discharge end. This is where the screening efficiency is achieved. These screens are generally large and used in high tonnage plants, particularly in mining where fewer fractions are separated.

There are a number of special screens, of which the flip flop is an example. The special narrow rubber mesh strips are installed perpendicularly between two separate frames. The meshes being attached to one frame on one side and to the other at the other side the bulk receives extremely high accelerations. This helps screening of wet, dirty and other difficult materials.

This table is a guide only to the parameters of a horizontal screen. When solving screening problems, take also into account the size parameters of the material, screen cloths and physical screening conditions.

wholesale conveyor with scale manufacturers and factory - suppliers direct price | jinte

wholesale conveyor with scale manufacturers and factory - suppliers direct price | jinte

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