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top 250+ electrician interview questions and answers 10 july 2021 - electrician interview questions | wisdom jobs india

Do you completed your graduation? Looking for job? Then electrician job is a good choice for you. Searching for low stress ways to get succeed for electrician job interviews? An electrician is a tradesman specializing in electrical things. Electricians may be employed in the installation of new electrical components or the maintenance and repair of existing electrical infrastructure. Electricians may also specialize in wiring ships and airplanes. There are many electrician jobs available in wisdom jobs such as ITI electrician, AV technician, BMS operator and HVAC operator etc.Electrician job role involves Assemble, install, test, and maintain electrical or electronic wiring, equipment, appliances, apparatus, and fixtures, using hand tools and power tools. Please have a look at our electrician job interview question and answers page to crack in your interview.

Answer :The rotary kiln in the application area, the numbers to be most cement industry. The whole process of cement production line summarized as 'two ground a burn,' with 'a burning,' is made by grinding good raw material, in the high temperature of kiln under the action of the process of burning become clinker. The equipment is also widely used in metallurgical, chemical, building, refractory material, environmental protection, and other industries. The rotary kiln under high temperature overloaded alternating slow operation, and its annex equipment maintenance and thermal rail system related to the level of control of the rotary kiln working safety and efficiency. Therefore, rotary kiln cement produces the host, commonly known as the cement factory 'heart'.Rotary kiln cement industry forged in the main equipment burn the cement clinker. The stand or fall of sealing device directly affects the thermal rail system and run the rotary kiln capital. Strengthen rotary kiln daily maintenance data analysis of the pack; be helpful for equipment management work. Cement kiln is used for making of cement clinker and there are dry and wet methods to make cement. Metallurgy chemical kiln is used in metallurgy industry and ironworks for lean iron ore, chromium ore and ferronickel ore calcimine. Rotary kiln is used for calcimine of high aluminum vandal ochre in refractory material industry; for calcimine of calotte and aluminum hydroxide in aluminum manufacturer; for claiming of chrome sand ore and chrome powder ore in chemical plant.Lime kiln is used for baking active lime and dolomite in the steel factory and ferroalloy factory. Rotary kiln is the main equipment for calcining cement clinker and it can be used widely for cement industry ,metallurgy industry ,chemical industry , etc.Which can be divided into cement kiln ,metallurgy chemical kiln and lime kiln according to different materials.

The rotary kiln in the application area, the numbers to be most cement industry. The whole process of cement production line summarized as 'two ground a burn,' with 'a burning,' is made by grinding good raw material, in the high temperature of kiln under the action of the process of burning become clinker. The equipment is also widely used in metallurgical, chemical, building, refractory material, environmental protection, and other industries.

The rotary kiln under high temperature overloaded alternating slow operation, and its annex equipment maintenance and thermal rail system related to the level of control of the rotary kiln working safety and efficiency. Therefore, rotary kiln cement produces the host, commonly known as the cement factory 'heart'.Rotary kiln cement industry forged in the main equipment burn the cement clinker. The stand or fall of sealing device directly affects the thermal rail system and run the rotary kiln capital. Strengthen rotary kiln daily maintenance data analysis of the pack; be helpful for equipment management work.

Cement kiln is used for making of cement clinker and there are dry and wet methods to make cement. Metallurgy chemical kiln is used in metallurgy industry and ironworks for lean iron ore, chromium ore and ferronickel ore calcimine. Rotary kiln is used for calcimine of high aluminum vandal ochre in refractory material industry; for calcimine of calotte and aluminum hydroxide in aluminum manufacturer; for claiming of chrome sand ore and chrome powder ore in chemical plant.Lime kiln is used for baking active lime and dolomite in the steel factory and ferroalloy factory.

Rotary kiln is the main equipment for calcining cement clinker and it can be used widely for cement industry ,metallurgy industry ,chemical industry , etc.Which can be divided into cement kiln ,metallurgy chemical kiln and lime kiln according to different materials.

Answer :Fuse: A fuse has a wire that melts with the heat of a short circuit or high current and interrupts the circuit. Once melted, you have to replace it. Circuit Breaker: A circuit breaker interrupts the current without melting ( a pair of metal sheets with different thermal expansion coefficient, for example) and can be reset.

Answer :We provide the following: Residential electrical work, central heating, cooling and air filtration Convenient, secure online self-scheduling for all your electrical needs Extended hours of operation: 7am -7pm Discounted member rates on labor and services A Home Electrical Safety Survey of all electrical systems for members.

Answer :This is used to describe the size and quantity of conductors in a cable. The first number specifies the gauge. The second the number of current carrying conductors in the wire - but remember there's usually an extra ground wire. "14-2" means 14 gauge, two insulated current carrying wires, plus bare ground. 2 wire usually has a black, white and bare ground wire. Sometimes the white is red instead for 220V circuits without neutral. In the latter case, the sheath is usually red too. 3 wire usually has a black, red, white and bare ground wire. Usually carrying 220V with neutral.

This is used to describe the size and quantity of conductors in a cable. The first number specifies the gauge. The second the number of current carrying conductors in the wire - but remember there's usually an extra ground wire. "14-2" means 14 gauge, two insulated current carrying wires, plus bare ground.

Answer :Statistics show that fuse panels have a significantly higher risk of causing a fire than breaker panels. This is usually due to the fuse being loosely screwed in, or the contacts corroding and heating up over time, or the wrong size fuse being installed, or the proverbial "replace the fuse with a penny" trick. Since breakers are more permanently installed, and have better connection mechanisms, the risk of fire is considerably less. Fuses are prone to explode under extremely high overload. When a fuse explodes, the metallic vapor cloud becomes a conducting path. Result? From complete meltdown of the electrical panel, melted service wiring, through fires in the electrical distribution transformer and having your house burn down.Breakers won't do this.

Statistics show that fuse panels have a significantly higher risk of causing a fire than breaker panels. This is usually due to the fuse being loosely screwed in, or the contacts corroding and heating up over time, or the wrong size fuse being installed, or the proverbial "replace the fuse with a penny" trick.

Fuses are prone to explode under extremely high overload. When a fuse explodes, the metallic vapor cloud becomes a conducting path. Result? From complete meltdown of the electrical panel, melted service wiring, through fires in the electrical distribution transformer and having your house burn down.Breakers won't do this.

Answer :Fuses and circuit breakers are designed to interrupt the power to a circuit when the current flow exceeds safe levels. For example, if your toaster shorts out, a fuse or breaker should "trip", protecting the wiring in the walls from melting. As such, fuses and breakers are primarily intended to protect the wiring -- UL or CSA approval supposedly indicates that the equipment itself won't cause a fire. Fuses contain a narrow strip of metal which is designed to melt (safely) when the current exceeds the rated value, there by interrupting the power to the circuit. Fuses trip relatively fast. Which can sometimes be a problem with motors which have large startup current surges. For motor circuits, you can use a "time-delay" fuse (one brand is "fusetron") which will avoid tripping on momentary overloads. A fusetron looks like a spring-loaded fuse. A fuse can only trip once, then it must be replaced.

Fuses and circuit breakers are designed to interrupt the power to a circuit when the current flow exceeds safe levels. For example, if your toaster shorts out, a fuse or breaker should "trip", protecting the wiring in the walls from melting. As such, fuses and breakers are primarily intended to protect the wiring -- UL or CSA approval supposedly indicates that the equipment itself won't cause a fire.

Fuses contain a narrow strip of metal which is designed to melt (safely) when the current exceeds the rated value, there by interrupting the power to the circuit. Fuses trip relatively fast. Which can sometimes be a problem with motors which have large startup current surges. For motor circuits, you can use a "time-delay" fuse (one brand is "fusetron") which will avoid tripping on momentary overloads. A fusetron looks like a spring-loaded fuse. A fuse can only trip once, then it must be replaced.

Answer :Inside the panel, connections are made to the incoming wires. These connections are then used to supply power to selected portions of the home. There are three different combinations: one hot, one neutral, and ground: 110V circuit. two hots, no neutral, and ground: 220V circuit. two hots, neutral, and ground: 220V circuit + neutral, and/or two 110V circuits with a common neutral.

Answer :In general, there is no requirement to upgrade older dwellings, though there are some exceptions (ie: smoke detectors in some cases). However, any new work must be done according to the latest electrical code. Also, if you do ``major'' work, you may be required to upgrade certain existing portions or all of your system. Check with your local electrical inspector.

In general, there is no requirement to upgrade older dwellings, though there are some exceptions (ie: smoke detectors in some cases). However, any new work must be done according to the latest electrical code. Also, if you do ``major'' work, you may be required to upgrade certain existing portions or all of your system. Check with your local electrical inspector.

Answer :Every electrical device or component must be certified by the Canadian Standards Association (or recognized equivalent) before it can be sold in Canada. Implicit in this is that all wiring must be done with CSA-approved materials. They perform testing similar to the UL (a bit more stringent), except that CSA (or recognized equivalent) approval is required by law. Again, like the UL, if a fire was caused by non-CSA-approved equipment, your insurance company may not have to pay the claim. Note: strictly speaking, there usually is a legal way around the lack of a CSA sticker. In some cases (eg: Ontario), a local hydro inspection prior to purchase, or prior to use, is acceptable. The hydro inspector will affix a "hydro sticker" to the unit, which is as good as CSA approval. But it costs money - last I knew, $75 per unit inspected.

Every electrical device or component must be certified by the Canadian Standards Association (or recognized equivalent) before it can be sold in Canada. Implicit in this is that all wiring must be done with CSA-approved materials. They perform testing similar to the UL (a bit more stringent), except that CSA (or recognized equivalent) approval is required by law.

Note: strictly speaking, there usually is a legal way around the lack of a CSA sticker. In some cases (eg: Ontario), a local hydro inspection prior to purchase, or prior to use, is acceptable. The hydro inspector will affix a "hydro sticker" to the unit, which is as good as CSA approval. But it costs money - last I knew, $75 per unit inspected.

Answer :The UL stands for "Underwriters Laboratory". It used to be an Insurance Industry organization, but now it is independent and non-profit. It tests electrical components and equipment for potential hazards. When something is UL-listed, that means that the UL has tested the device, and it meets their requirements for safety - ie: fire or shock hazard. It doesn't necessarily mean that the device actually does what it's supposed to, just that it probably won't kill you. The UL does not have power of law in the U.S. -- you are permitted to buy and install non-UL-listed devices. However, insurance policies sometimes have clauses in them that will limit their liability in case of a claim made in response to the failure of a non-UL-listed device. Furthermore, in many situations the NEC will require that a wiring component used for a specific purpose is UL-listed for that purpose. Indirectly, this means that certain parts of your wiring must be UL-listed before an inspector will approve it and/or occupancy permits issued.

The UL stands for "Underwriters Laboratory". It used to be an Insurance Industry organization, but now it is independent and non-profit. It tests electrical components and equipment for potential hazards. When something is UL-listed, that means that the UL has tested the device, and it meets their requirements for safety - ie: fire or shock hazard. It doesn't necessarily mean that the device actually does what it's supposed to, just that it probably won't kill you.

The UL does not have power of law in the U.S. -- you are permitted to buy and install non-UL-listed devices. However, insurance policies sometimes have clauses in them that will limit their liability in case of a claim made in response to the failure of a non-UL-listed device. Furthermore, in many situations the NEC will require that a wiring component used for a specific purpose is UL-listed for that purpose. Indirectly, this means that certain parts of your wiring must be UL-listed before an inspector will approve it and/or occupancy permits issued.

Answer :The NEC is a model electrical code devised and published by the National Fire Protection Association, an insurance industry group. It's revised every three years. The 1993 version has been released. You can buy a copy at a decent bookstore, or by calling them directly at 800-344-3555. The code exists in several versions. There's the full text, which is fairly incomprehensible. There's an abridged edition, which has only the sections likely to apply to most houses. And there's the NEC Handbook, which contains the ``authorized commentary'' on the code, as well as the full text. That's the recommended version. Unfortunately, there's no handbook for the abridged edition. And the full handbook is expensive --US$65 plus shipping and handling.

The NEC is a model electrical code devised and published by the National Fire Protection Association, an insurance industry group. It's revised every three years. The 1993 version has been released. You can buy a copy at a decent bookstore, or by calling them directly at 800-344-3555. The code exists in several versions. There's the full text, which is fairly incomprehensible. There's an abridged edition, which has only the sections likely to apply to most houses. And there's the NEC Handbook, which contains the ``authorized commentary'' on the code, as well as the full text. That's the recommended version. Unfortunately, there's no handbook for the abridged edition. And the full handbook is expensive --US$65 plus shipping and handling.

Answer :It's OK to visit the hardware shop and buy the switch you like the look of. But you need a licensed electrician to complete the work. A licensed electrician will issue a certificate to show the work complies with building standards. That way your property won't be devalued or insurance issues crop up in the event of a problem.

It's OK to visit the hardware shop and buy the switch you like the look of. But you need a licensed electrician to complete the work. A licensed electrician will issue a certificate to show the work complies with building standards. That way your property won't be devalued or insurance issues crop up in the event of a problem.

Answer :An electrical contractor can install solar panels to your property. Excess energy collected by your solar panels is fed into the electrical grid. You receive credit for power generated on your electricity bill.

An electrical contractor can install solar panels to your property. Excess energy collected by your solar panels is fed into the electrical grid. You receive credit for power generated on your electricity bill.

Answer :Electrician is a trade qualification and electrical contractors are licensed in each state. Many electricians also choose to belong to professional associations like NECA (National Electrical & Communications Association).

Electrician is a trade qualification and electrical contractors are licensed in each state. Many electricians also choose to belong to professional associations like NECA (National Electrical & Communications Association).

Answer :Be sure to hire a licensed professional electrician. There a several reasons for this: you'll get a better job work will comply with the building code you won't have an insurance problems if something goes wrong.

Answer :One of the best ways to save money on electrician costs is to do some research. Find out how much electrician companies and individual electricians charge for their services. Compare quotes between different electrician service providers and determine which one is best for your budget. You can learn more tips from our Work and Costs section.

One of the best ways to save money on electrician costs is to do some research. Find out how much electrician companies and individual electricians charge for their services. Compare quotes between different electrician service providers and determine which one is best for your budget. You can learn more tips from our Work and Costs section.

Answer :Absolutely. A valid professional license is the ultimate proof of your electrician's qualifications. Without one, your electrician can't assure you that he has gone through the requisite training and tests that would enable him to perform at a high standard and in accordance with the NEC. Never hire an unlicensed electrician if you're after quality service. (Refer to our Electrician Licensing page for more on this.)

Absolutely. A valid professional license is the ultimate proof of your electrician's qualifications. Without one, your electrician can't assure you that he has gone through the requisite training and tests that would enable him to perform at a high standard and in accordance with the NEC. Never hire an unlicensed electrician if you're after quality service. (Refer to our Electrician Licensing page for more on this.)

Answer :His years of studying, training, and gaining relevant experience. An electrician needs to complete school and spend years (or the equivalent of several thousand working hours) as an apprentice before he even becomes eligible for a license. Add the skill and experience he developed after acquiring his license, and you should be confident that he can serve you well.

His years of studying, training, and gaining relevant experience. An electrician needs to complete school and spend years (or the equivalent of several thousand working hours) as an apprentice before he even becomes eligible for a license. Add the skill and experience he developed after acquiring his license, and you should be confident that he can serve you well.

Answer :Electricians have varying levels of experience and qualifications. There are apprentices, Journeyman electricians, and Master electricians. An apprentice is still required to work under the supervision of a Journeyman and Master electrician. A Journeyman electrician has extensive knowledge of various electrical fields and can work unsupervised, but he is still not sufficiently qualified to take on electrical projects of utmost complexity. A master electrician is fully qualified to handle any electrical project. Your electrician's experience should at least be directly proportional to the difficulty of the job you need to have done.

An apprentice is still required to work under the supervision of a Journeyman and Master electrician. A Journeyman electrician has extensive knowledge of various electrical fields and can work unsupervised, but he is still not sufficiently qualified to take on electrical projects of utmost complexity. A master electrician is fully qualified to handle any electrical project. Your electrician's experience should at least be directly proportional to the difficulty of the job you need to have done.

Answer :When dealing with an electrical problem, it's best to contact a licensed professional at once. If you try to solve the problem on your own, you could jeopardize your safety as well as that of your electrical system and equipment. And though it's not as urgent, electrical installation of any kind also merits expert assistance. It's likely that you don't want to hire an electrician because of the expense, but that plan could easily backfire. Any mistakes you make may lead to damages that will only cost you more in the long run.

When dealing with an electrical problem, it's best to contact a licensed professional at once. If you try to solve the problem on your own, you could jeopardize your safety as well as that of your electrical system and equipment. And though it's not as urgent, electrical installation of any kind also merits expert assistance.

It's likely that you don't want to hire an electrician because of the expense, but that plan could easily backfire. Any mistakes you make may lead to damages that will only cost you more in the long run.

ncert solutions for class 10 geography social science chapter 6 manufacturing industries - free pdf

Students who are finding it difficult to get the answers to the exercise questions of Class 10 Geography Chapter 6 can refer to theNCERT Solutions for Class 10 Geography Chapter 6 Manufacturing Industries. These solutions contain the answers to all the questions in a descriptive way. Answers are provided in a simple language and in an expressive way so that students can easily understand it. Referring to these answers will help students in scoring high marks in the Social Science exam.

Manufacturing is the production of goods in large quantities after processing from raw materials to more valuable products. For e.g.,- paper is manufactured from wood, sugar from sugarcane, iron and steel from iron ore and aluminium from bauxite.

Frequently Asked Questions on NCERT Solutions for Class 10 Geography Chapter 6How many questions are present in NCERT Solutions for Class 10 Geography Chapter 6?The second chapter of NCERT Solutions for Class 10 Geography Sectors of the Economy has 3 main questions and more sub questions in total. Among these, the first question is of the type MCQ containing 4 sub-questions and the remaining are short and long answers type questions.Where can I find the correct NCERT Solutions for Class 10 Geography Chapter 6 online?The NCERT Solutions for Class 10 Geography Chapter 6 can be found by students on BYJUS website. These NCERT Solutions are one among the top-rated study materials available online for free. Students can undoubtedly rely upon these for their exam preparations. To refer the solutions offline, the PDFs containing solutions are made available to students for free download and can be accessed at any time. All the solutions have been curated by subject matter experts at BYJUS carefully based on the latest syllabus of the CBSE board.Are NCERT Solutions for Class 10 Geography Chapter 6 effective for the board exam preparation?The NCERT Solutions aid students to strengthen their foundation in the fundamental topics of Geography. The answers to behind text questions are designed by highly knowledgeable experts in the subject at BYJUS having vast experience. These solutions will definitely improve the focus among students and help them score well in the board exams.

laboratory grinding mill

Our Laboratory Grinding Mill comes standard with a 1 HP motor and optional variable speed drive ranging from 1 to 100 RPM. This Grinding Mill is fully enclosed with sound dampening material for a quiet workplace. The sheet metal steel fabrication provides full enclosure around the main frame and door. The yoke (grinding cylinder) is totally balance and vibration-free in its horizontal position of operation. Minimal effort is needed to swing it from horizontal to vertical position (loading/unloading). A unique feature this grinding mill has is the possibility to use different cylinders for research or pilot plants tests. Specifically, we offer different size of cylinders from 5 (127mm) inside diameter by 12 (305mm) long to 9 (229mm) diameter by 22 (560mm) long. All grinding mills cylinders are fully interchangeable and can be mounted/ removed rapidly. The cover is of a unique design that automatically seals the cylinder and is quickly mounted/removed. Another feature of this Grinding Mill are its heavy duty castors (wheels) for ease of laboratory movement/mobility.

Ore Grinding Mills are used for the fine grinding as the last step in the reduction of an ore prior to concentration (gravity or flotation) or cyanidation. Practice varies, depending upon the type of ore and the amount of reduction required. In addition, some of the older properties continue with methods that perhaps are not considered the best in light of recent improvements but that cannot be economically changed because of capital outlay. Present grinding practice is closely linked with classification, so that some overlapping of subject matter occurs. In this chapter some of the theory of grinding, different types of equipment, and flow sheets are discussed.

Most of the tonnage milled today is ground in one of the following types of equipment or a combination of two or more: ball mills, tube mills, rod mills, and stamps. Chilean mills and Huntington mills are used only in a few isolated cases today.

The term ball mill is generally used to refer to a cylindrical mill whose length is less than, equal to, but not much greater than its diameter. It was initially developed for relatively coarse grinding, but by using it in closed circuit with a classifier its use has been extended for fine grinding.

Ball mills have shells of cast iron or steel plates and are carried on hollow trunnions. Ore is fed through a scoop, drum-type, or combination feeder at one end and is discharged from the opposite trunnion.

Ball mills may be arbitrarily classified into two types, according to the method of pulp discharge. In high-level or overflow mills the pulp level builds up until it overflows and discharges through the trunnion. High- level discharge mills are made by a large number of manufacturers throughout the world. Low-level mills are typified by the Allis-Chalmers andMarcy (see Figs. 14 and 15) grate-discharge mills. The discharge end is fitted with grates; between the grates and the end of the mill are radial lifters which act as a pump to lift the discharge to the hollow trunnion. Drive is by spur or herringbone gear, direct connected or belt driven.

Ball mills are built in sizes ranging from small laboratory mills to a present maximum of 12 ft. diameter by 12 ft. long, the latter requiring close to 1000 hp.Liners are usually of manganese steel, of chrome steel, or white iron, 3 to 6 in. thick. Corrugated and shiplap construction is commonly used to increase the grinding action.

The Hardinge mill (see Fig. 16) differs from most ball mills in that conical ends are added to the cylindrical portion of the mill. The cone at the feed end has a larger open angle than that at theopposite end. Its makers state that the large balls concentrate near the feed end of the mill where the coarsest ore collects and the smaller balls act on the finer ore.

Rod mills (see Fig. 17) follow the general dimensions of tube mills with diameters from 3 to 6 ft. and lengths from two to three times their diameter. They differ from ball mills in that steel rods 3 or 4 in. shorter than the mill length inside the liners are used as grinding media. Rod mills are often run on tires and rollers instead of trunnions or on one trunnion and one tire and set of rollers.

Low-level discharge is obtained on Marcy rod mills by having a beveled annular ring at the discharge end. A stationary steel door fits close to this beveled ring and serves to hold the rods in the mill while pulp discharges between the mill and the door.

The distinction between tube mills and ball mills is not somarked as their names indicate. Mills from 4 to 6 ft. in diameter and from 16 to 22 ft. long are usually termed tube mills. This was the first type of rotary mill for metallurgical purposes. Because of the necessity of completing the grind during one passage (open circuit) of the ore through the mill, it was built with a large length-diameter ratio. The tube mill is still largely used in South Africa and to some extent in North America for fine grinding generally following some other primary mills.

Tube mills are usually supported on hollow trunnions, the feed entering through a feed scoop at one end and discharging through the other. Drive is by a large gear fitted over the mill shell. Various types of liners are used, as in ball mills.

All rotary mills must be fitted with some kind of replaceable liners. Chrome steel, manganese steel, and white iron are generally used. Shapes designed to give a corrugated or shiplap surface to the interior of the mill are often used to prevent slippage of the ball load. Pocket liners arealso common. These liners have pockets in which the balls become lodged to form the wearing surface.

Rubber liners have been tried experimentally but have not been adopted by the industry. According to Taggart, no fully satisfactory method of holding the liners in place was worked out, utility was limited to fine feeds and small balls, mill capacity was reduced, and while a slightly higher grinding efficiency was shown in comparative tests with steel liners, there was no indication that possible increased wear for rubber would offset its far greater cost.Silex liners with flint pebbles for grinding media are sometimes used where iron contamination must be avoided.

The grinding that takes place in mills of this type is usually ascribed to two actions, impact and attrition, although some authors do not believe that a sharp line of demarcation can be drawn between the two actions.

In rod mills there is line contact between the rods, there is less grinding by impact, and the action resembles that of crushing rolls. As a result, a rod-mill product usually contains a greater percentage near the limiting size with less extreme fines than ball or tube mills.

In selecting the correct grinding media it is important that the rods or balls supplied be large enough to break the largest particles of ore in the feed, and as already discussed, a seasoned load composed of balls of all sizes, which is the condition found in a mill that has been operating for some time, gives better grinding efficiency than a new charge.

The volume of the charge is limited to a maximum of about 50 per cent of the mill volume. If the charge is too large, its center of gravity shifts too near the axis of the mill and the power input falls.

The speed of the mill is limited by what is known as the critical speed. This is the speed at which (assuming no slippage) the charge starts to cling to the liners, or to centrifuge. It is given by the formula.

The percentage of solids in the pulp is usually maintained at 60 to 75 per cent, the principle being to keep the volume percentage of solids as high as possible without loss of mobility of the charge. The correct proportion of water present will depend on the kind of ore being handled, slimy ores in general requiring a higher dilution than ores that have a low slime content.

The size of mill required for a specific grinding problem will depend on the character and size of the feed and the product desired and whether open- or closed-circuit grinding is desired. An accurate estimate of capacity can be made only by an engineer familiar with the proper evaluation of the factors involved.

For rough estimating purposes Table 6 gives approximate capacities grinding to 48 and 100 mesh for several size mills. Connected horsepower is also shown. These figures are for what would normally be considered average siliceous ore and for nominal circulating loads of 2 or 3 to 1.

These capacities may be reduced by as much as 50 per cent in the case of a hard, tough ore which is highly resistant to grinding, and for this reason considerable thought has in recent years been given to methods for determining the relative grindability of different ores and to correlating laboratory figures with plant performance. F. C. Bond has published comprehensive grindability data based on work carried out by the Allis-Chalmers Manufacturing Co. and grindability tests are a regular part of the testing procedure of the Dorr Company at the Westport, Conn., laboratories.

When the tube mill was first introduced, grinding was done in open circuit; i.e., the ore was ground to pass the limiting screen size by one passage through the mill. It was found, however, that if sufficient time of contact between the ore and grinding media were provided to ensure that no unground particles (or oversize) discharged from the mill, an excessive amount of fines were produced. This meant that the ore was ground much finer than necessary and mill capacity was correspondingly reduced.

The difficulty was overcome by placing a classifier in the circuit to separate out oversize from the mill discharge and return it to the mill feed. In closed-circuit grinding no attempt is made to finish the grind in one passage through the mill, but every effort is made to remove finished material as soon as it is released, thus reducing over-grinding and preventing the fines from hindering the grinding action on yet unreduced particles. In this way the tonnage that a given mill will grind is much greater than it is possible to grind in open circuit.

By using wide classifiers with high raking capacity, circulating-load ratios are now being carried to 4:1 or higher. The direct result of the increased capacity is reduced power, liner, and grinding media consumption per ton of finished ore.

There is, of course, a limit as to how large a circulating load can be carried in practice. While capacity continues apparently to improve, though at a decreased rate, it becomes increasingly difficult to move the growing volume of material through the system.

There is some controversy in the literature as to the definition of ratio ofcirculating load. The term used by most millmen is the ratio of sand tonnage returned to the mill to the tons of original feed.

If the mill-classifier circuit is fed into the classifier instead of into the mill, the sand contains oversize from the original feed as well as oversize from mill discharge, and thus the definition is not entirely accurate. The ratio of circulating load can be calculated from screen analyses by using the following formulas:

Circulating-load ratio = d o/s d where d = cumulative percentage 0n any mesh in the mill discharge o = cumulative percentage on same mesh in the classifier overflow s = cumulative percentage on same mesh in the classifier sand

There are many types of flow sheets in use today. The tendency in new mills is to crush relatively fine ( to in.). Single-stage ball mills in closed circuit with classifiers are used for grinds coarser than 48 mesh, but when a finer product is desired, two stages of ball mills in closed circuit with classifiers is usual. Efficiency must necessarily be sacrificed to some extent in small mills by capital requirements, and even greater reduction ratios are justified in a single-stage grinding unit.

With the large classifiers used for high circulating loads it is quite often necessary to use some kind of auxiliary device to complete the closed circuit. A large motor-driven scoop lifting the mill discharge to the classifier has been successful.

Stamp mills were built to parallel the operation of a mortar and pestle, working continuously and on a large scale. Ore is fed into a mortar and is crushed by the dropping of the stamp on a die at the bottom of the mortar. The crushed ore discharges through a screen in the side of the mortar.

The shoe that forms the wearing surface on the dropping stamp is attached to a steel stem and is replaceable. The stem is lifted by a cam operating against a tappet which is bolted to the stem. A common camshaft activates usually five stamps in a battery.

Milling was done in unique, crude wooden stamp mills developed by the ingenious Antioquenan miner. Made entirely of hand-hewn hardwrnod (except for cast-iron shoes, several bolts, and a few nails) these molinos Antioquenos have a stamp duty of approximately 0.4 tons per 24 hr. They are powered by overshot water wheels, 18 to 24 ft. in diameter, mounted directly on the 18- to 24-in. wooden camshaft of the mill. Up to 56 drops per minute can be obtained with a water-wheel speed of 14 r.p.m. The stamps, 6 by 7 in. by 14 ft. in dimensions, weigh 450 to 500 lb. including the cast-iron shoe. The mills are usually built with three stamps to the mortar box and as many as three sets (nine stamps) per mill. Battery-box screens are usually made of tin from 5-gal. gasoline cans perforated with a small nail. Stamp guides, cams, and the hardwood camshaft bearings are lubricated with beef tallow.

The stamp mill was originally devised as a combination grinding and amalgamating device before the days of cyanidation. Its use continued with theintroduction of the cyanide process, where it was well suited to the comparatively coarse crushing used, the distribution of the ground pulp over amalgamation plates, and the steps of separate cyanidation of sand and slimes that followed. As the all-sliming method became more generally adopted, however, with the need for fine grinding in ball mills and preferably in cyanide solution, the stamp mill tended either to be used as a secondary crusher or to be replaced altogether by dry-crushing equipment.

These two types of mill are practically obsolete. In these mills rollers driven from a central gear-driven spindle revolve around a pan. In the former the rolls crush against a ring in the bottom of the pan, and in the latter centrifugal force holds the rollers against the ring at the side of the pan. Chilean mills were used at the Golden Cycle up to a few years ago for grinding roasted ore.

iron ore processing,crushing,grinding plant machine desgin&for sale | prominer (shanghai) mining technology co.,ltd

After crushing, grinding, magnetic separation, flotation, and gravity separation, etc., iron is gradually selected from the natural iron ore. The beneficiation process should be as efficient and simple as possible, such as the development of energy-saving equipment, and the best possible results with the most suitable process. In the iron ore beneficiation factory, the equipment investment, production cost, power consumption and steel consumption of crushing and grinding operations often account for the largest proportion. Therefore, the calculation and selection of crushing and grinding equipment and the quality of operation management are to a large extent determine the economic benefits of the beneficiation factory.

There are many types of iron ore, but mainly magnetite (Fe3O4) and hematite (Fe2O3) are used for iron production because magnetite and hematite have higher content of iron and easy to be upgraded to high grade for steel factories.

Due to the deformation of the geological properties, there would be some changes of the characteristics of the raw ore and sometimes magnetite, hematite, limonite as well as other types iron ore and veins are in symbiosis form. So mineralogy study on the forms, characteristics as well as liberation size are necessary before getting into the study of beneficiation technology.

1. Magnetite ore stage grinding-magnetic separation process The stage grinding-magnetic separation process mainly utilizes the characteristics of magnetite that can be enriched under coarse grinding conditions, and at the same time, it can discharge the characteristics of single gangue, reducing the amount of grinding in the next stage. In the process of continuous development and improvement, the process adopts high-efficiency magnetic separation equipment to achieve energy saving and consumption reduction. At present, almost all magnetic separation plants in China use a large-diameter (medium 1 050 mm, medium 1 200 mm, medium 1 500 mm, etc.) permanent magnet magnetic separator to carry out the stage tailing removing process after one stage grinding. The characteristic of permanent magnet large-diameter magnetic separator is that it can effectively separate 3~0mm or 6~0mm, or even 10-0mm coarse-grained magnetite ore, and the yield of removed tails is generally 30.00%~50.00%. The grade is below 8.00%, which creates good conditions for the magnetic separation plant to save energy and increase production.

2.Magnetic separation-fine screen process Gangue conjoined bodies such as magnetite and quartz can be enriched when the particle size and magnetic properties reach a certain range. However, it is easy to form a coarse concatenated mixture in the iron concentrate, which reduces the grade of the iron concentrate. This kind of concentrate is sieved by a fine sieve with corresponding sieve holes, and high-quality iron concentrate can be obtained under the sieve.

There are two methods for gravity separation of hematite. One is coarse-grained gravity separation. The geological grade of the ore deposit is relatively high (about 50%), but the ore body is thinner or has more interlayers. The waste rock is mixed in during mining to dilute the ore. For this kind of ore, only crushing and no-grinding can be used so coarse-grained tailings are discarded through re-election to recover the geological grade.

The other one is fine-grain gravity separation, which mostly deals with the hematite with finer grain size and high magnetic content. After crushing, the ore is ground to separate the mineral monomers, and the fine-grained high-grade concentrate is obtained by gravity separation. However, since most of the weak magnetic iron ore concentrates with strong magnetic separation are not high in grade, and the unit processing capacity of the gravity separation process is relatively low, the combined process of strong magnetic separation and gravity separation is often used, that is, the strong magnetic separation process is used to discard a large amount of unqualified tailings, and then use the gravity separation process to further process the strong magnetic concentrate to improve the concentrate grade.

Due to the complexity, large-scale mixed iron ore and hematite ore adopt stage grinding or continuous grinding, coarse subdivision separation, gravity separation-weak magnetic separation-high gradient magnetic separation-anion reverse flotation process. The characteristics of such process are as follows:

(1) Coarse subdivision separation: For the coarse part, use gravity separation to take out most of the coarse-grained iron concentrate after a stage of grinding. The SLon type high gradient medium magnetic machine removes part of the tailings; the fine part uses the SLon type high gradient strong magnetic separator to further remove the tailings and mud to create good operating conditions for reverse flotation. Due to the superior performance of the SLon-type high-gradient magnetic separator, a higher recovery rate in the whole process is ensured, and the reverse flotation guarantees a higher fine-grained concentrate grade.

(2) A reasonable process for narrow-level selection is realized. In the process of mineral separation, the degree of separation of minerals is not only related to the characteristics of the mineral itself, but also to the specific surface area of the mineral particles. This effect is more prominent in the flotation process. Because in the flotation process, the minimum value of the force between the flotation agent and the mineral and the agent and the bubble is related to the specific surface area of the mineral, and the ratio of the agent to the mineral action area. This makes the factors double affecting the floatability of minerals easily causing minerals with a large specific surface area and relatively difficult to float and minerals with a small specific surface area and relatively easy to float have relatively consistent floatability, and sometimes the former has even better floatability. The realization of the narrow-level beneficiation process can prevent the occurrence of the above-mentioned phenomenon that easily leads to the chaos of the flotation process to a large extent, and improve the beneficiation efficiency.

(3) The combined application of high-gradient strong magnetic separation and anion reverse flotation process achieves the best combination of processes. At present, the weak magnetic iron ore beneficiation plants in China all adopt high-gradient strong magnetic separation-anion reverse flotation process in their technological process. This combination is particularly effective in the beneficiation of weak magnetic iron ore. For high-gradient strong magnetic separation, the effect of improving the grade of concentrate is not obvious. However, it is very effective to rely on high-gradient and strong magnetic separation to provide ideal raw materials for reverse flotation. At the same time, anion reverse flotation is affected by its own process characteristics and is particularly effective for the separation of fine-grained and relatively high-grade materials. The advantages of high-gradient strong magnetic separation and anion reverse flotation technology complement each other, and realize the delicate combination of the beneficiation process.

The key technology innovation of the integrated dry grinding and magnetic separation system is to "replace ball mill grinding with HPGR grinding", and the target is to reduce the cost of ball mill grinding and wet magnetic separation.

HPGRs orhigh-pressure grinding rollshave made broad advances into mining industries. The technology is now widely viewed as a primary milling alternative, and there are several large installations commissioned in recent years. After these developments, anHPGRsbased circuit configuration would often be the base case for certain ore types, such as very hard, abrasive ores.

The wear on a rolls surface is a function of the ores abrasivity. Increasing roll speed or pressure increases wear with a given material. Studs allowing the formation of an autogenous wear layer, edge blocks, and cheek plates. Development in these areas continues, with examples including profiling of stud hardness to minimize the bathtub effect (wear of the center of the rolls more rapidly than the outer areas), low-profile edge blocks for installation on worn tires, and improvements in both design and wear materials for cheek plates.

With Strip Surface, HPGRs improve observed downstream comminution efficiency. This is attributable to both increased fines generation, but also due to what appears to be weakening of the ore which many researchers attribute to micro-cracking.

As we tested , the average yield of 3mm-0 and 0.15mm-0 size fraction with Strip Surface was 78.3% and 46.2%, comparatively, the average yield of 3mm-0 and 0.3mm-0 with studs surface was 58.36% and 21.7%.

These intelligently engineered units are ideal for classifying coarser cuts ranging from 50 to 200 mesh. The feed material is dropped into the top of the classifier. It falls into a continuous feed curtain in front of the vanes, passing through low velocity air entering the side of the unit. The air flow direction is changed by the vanes from horizontal to angularly upward, resulting in separation and classification of the particulate. Coarse particles dropps directly to the product and fine particles are efficiently discharged through a valve beneath the unit. The micro fines are conveyed by air to a fabric filter for final recovery.

Air Magnetic Separation Cluster is a special equipment developed for dry magnetic separation of fine size (-3mm) and micro fine size(-0.1mm) magnetite. The air magnetic separation system can be combined according to the characteristic of magnetic minerals to achieve effective recovery of magnetite.

After rough grinding, adopt appropriate separation method, discard part of tailings and sort out part of qualified concentrate, and re-grind and re-separate the middling, is called stage grinding and stage separation process.

According to the characteristics of the raw ore, the use of stage grinding and stage separation technology is an effective measure for energy conservation in iron ore concentrators. At the coarser one-stage grinding fineness, high-efficiency beneficiation equipment is used to advance the tailings, which greatly reduces the processing volume of the second-stage grinding.

If the crystal grain size is relatively coarse, the stage grinding, stage magnetic separation-fine sieve self-circulation process is adopted. Generally, the product on the fine sieve is given to the second stage grinding and re-grinding. The process flow is relatively simple.

If the crystal grain size is too fine, the process of stage grinding, stage magnetic separation and fine sieve regrind is adopted. This process is the third stage of grinding and fine grinding after the products on the first and second stages of fine sieve are concentrated and magnetically separated. Then it is processed by magnetic separation and fine sieve, the process is relatively complicated.

At present, the operation of magnetic separation (including weak magnetic separation and strong magnetic separation) is one of the effective means of throwing tails in advance; anion reverse flotation and cation reverse flotation are one of the effective means to improve the grade of iron ore.

In particular, in the process of beneficiation, both of them basically take the selected feed minerals containing less gangue minerals as the sorting object, and both use the biggest difference in mineral selectivity, which makes the two in the whole process both play a good role in the process.

Based on the iron ore processing experience and necessary processing tests, Prominer can supply complete processing plant combined with various processing technologies, such as gravity separation, magnetic separation, flotation, etc., to improve the grade of TFe of the concentrate and get the best yield. Magnetic separation is commonly used for magnetite. Gravity separation is commonly used for hematite. Flotation is mainly used to process limonite and other kinds of iron ores

Through detailed mineralogy study and lab processing test, a most suitable processing plant parameters will be acquired. Based on those parameters Prominer can design a processing plant for mine owners and supply EPC services till the plant operating.

Prominer has been devoted to mineral processing industry for decades and specializes in mineral upgrading and deep processing. With expertise in the fields of mineral project development, mining, test study, engineering, technological processing.

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Ball mill and Rod mill is a tool used in modern mineral processing, coal chemical industry, sand making and other industries to grind ore into powder and then used in smelting industry to smelt gold, steel, etc. Coal chemical industry coal water slurry is gasified to make chemical raw materials, and sand making is used []

Recently, my friend asked how should we choose the diameter of the steel grinding rod in the rod mill?. In fact, this is a rather complicated problem, which is not only related to the rod mill, but also has a great relationship with working conditions (feed particle size, discharge fineness, hardness of ore type, effective []

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Jinan zhongnai grinding technology co., ltd is a supplier specializing in grinding media for ball mill and rod mill. The main products include grinding rods, forged steel grinding balls, hot rolled steel grinding balls, cast steel balls, steel cylpebs and lining plates, etc.

All products of our company are supplied to users of ball mills and rod mills. We are looking for customers bulk purchase order and customization requirements. Usually personal retail requirements are not accepted. Copyright 2020 ZHONGNAI

iron ore grinding process,process design for grinding stage,closed circuit grinding technology | prominer (shanghai) mining technology co.,ltd

Generally, the conventional process can be applied except for ore with a lot of mud and high humidity. The self-grinding and semi-self-grinding processes have high power consumption and should be selected carefully.

There is no strict restriction on the upper limit and particle size distribution of the products in the open-circuit grinding process. Because the ore to be ground passes through the grinding machine only once, the product size is relatively coarse. This type of process is commonly used in the first stage of the single-stage rod milling process or the first stage of the two-stage grinding process with rod mills. The ore can be ground from 20-25 mm to about 3 mm at a time. The open-circuit grinding process is simple, the production capacity is large, no grading and return ore facilities are required, the construction speed is fast, the production operation and maintenance are easy, and it is generally used for rough grinding.

In closed-circuit grinding, the returned sand from the classifier is mostly finer than the original ore. The returned sand is mixed with the ore newly fed into the mill, so that the average particle size of the ore particles in the mill is reduced, and the content of ore particles close to the particle size of the grinding product increases. The gap around the coarse-grained ore is filled with fine-grained sand. It is beneficial to form a more favorable meshing between the crushing medium and the ore particles. Along the entire length of the grinding machine, the ratio of the size of the ball to the average diameter of the ore particles is relatively stable. The material flows faster in the grinding machine. Therefore, the productivity of the closed-circuit grinding machine is generally higher than that of the open-circuit grinding machine, and the product size is smaller. Fine, uniform particle size, less over-crushing. Closed-circuit grinding can also improve the selective grinding of heavy minerals.

The beneficiation practice shows that in each grinding section, the grinding ratio has a suitable value, and the grinding ratio of the conventional ball milling section is generally about 80-100. An excessively large primary grinding ratio is uneconomical. The grinding efficiency is low, the energy consumption is high, and the product is easily crushed, which affects the sorting effect and economic benefits. Practice has shown that the more difficult to grind the ore, the less economically reasonable it is to use one-stage grinding process for fine grinding. The two-stage grinding process can overcome the shortcomings of the one-stage grinding process. It can reasonably distribute the load according to the difference in the particle size of the materials in the grinding mills and the properties of the wear-resistant materials, and it is easy to select the appropriate medium size and ratio according to the different feed and product particle sizes of the two-stage mills.

When the grindability of the ore is very poor and the grinding particle size is required to be extremely fine, or the concentrate grade is required to be high and the ore is fine-grained or unevenly embedded, or the old concentrator wants to improve the original grinding When operating the production capacity, three-stage or multi-stage grinding process can be used. For ore that is extremely easy to slush, in order to improve the efficiency of grinding and beneficiation, prevent excessive crushing, and recover the dissociated useful minerals as soon as possible, the stage grinding and stage separation process can be used. In this way, the use of selective grinding can effectively recover useful minerals. Large-scale iron ore concentrators that adopt a staged grinding process can sort and discard coarse-grained tails after one stage of grinding if the iron ore properties are suitable.

Prominer has been devoted to mineral processing industry for decades and specializes in mineral upgrading and deep processing. With expertise in the fields of mineral project development, mining, test study, engineering, technological processing.