Peizometer

The piezometer is a device to measure pressure and the compressibility of liquids. This is a form devised by Regnault and was used to show that water is nearly incompressible.

Working principle:

In a typical installation, the piezometer is sealed in a borehole, embedded in fill, or suspended in a standpipe. Twin pneumatic tubes run from the piezometer to a terminal at the surface. Readings are obtained with a pneumatic indicator.The piezometer contains a flexible diaphragm. Water pressure acts on one side of the diaphragm and gas pressure acts on the other.When a reading is required, a pneumatic indicator is connected to the terminal or directly to the tubing.Compressed nitrogen gas from the indicator flows down the input tube to increase gas pressure on the diaphragm.When gas pressure exceeds water pressure, the diaphragm is forced away from the vent tube, allowing excess gas to escape via the vent tube.When the return flow of gas is detected at the surface, the gas supply is shut off. Gas pressure in the piezometer decreases until water pressure forces the diaphragm to its original position, preventing further escape of gas through the vent tube.At this point, gas pressure equals water pressure, and a reading can be obtained from the pressure gauge on the indicator.

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Limitations:

1). This can’t be used for gases.
2). Its diameter of tube should be more than 12mm.

3). It can use only for low pressures.

Pumps

These are such devices which are used to transfer of liquid from one place to another place (e.g. water from an underground aquifer into a water storage tank) and to circulate liquid around a system (e.g. cooling water or lubricants through machines and equipment).

The main components of a pumping system are:

�� Pumps

�� Prime movers: electric motors diesel engines or air system.

�� Piping, used to carry the fluid.

�� Valves, used to control the flow in the system.

�� Other fittings, controls and instrumentation.

�� End-use equipment, which have different requirements (e.g. pressure, flow) and therefore determine the pumping system components and configuration. Examples include heat exchangers, tanks and hydraulic machines.

The pump and the prime mover are typically the most energy inefficient components.

 

Types of pumps:-

Pumps come in a variety of sizes for a wide range of applications. They can be classified according to their basic operating principle as dynamic or positive displacement pumps.

In principle, any liquid can be handled by any of the pump designs. Where different pump designs could be used, the centrifugal pump is generally the most economical followed by rotary and reciprocating pumps. Although, positive displacement pumps are generally more efficient than centrifugal pumps, the benefit of higher efficiency tends to be offset by increased maintenance costs.

Positive displacement pumps:

Positive displacement pumps are distinguished by the way they operate: liquid is taken from one end and positively discharged at the other end for every revolution. Positive displacement pumps are widely used for pumping fluids other than water, mostly viscous fluids.

Positive displacement pumps are further classified based upon the mode of displacement:

�� Reciprocating pump if the displacement is by reciprocation of a piston plunger. Reciprocating pumps are used only for pumping viscous liquids and oil wells.

�� Rotary pumps if the displacement is by rotary action of a gear, cam or vanes in a chamber of diaphragm in a fixed casing. Rotary pumps are further classified such as internal gear, external gear, lobe and slide vane etc. These pumps are used for special services with particular conditions existing in industrial sites.

In all positive displacement type pumps, a fixed quantity of liquid is pumped after each revolution. So if the delivery pipe is blocked, the pressure rises to a very high value, which can damage the pump.

Dynamic pumps:

Dynamic pumps are also characterized by their mode of operation: a rotating impeller converts kinetic energy into pressure or velocity that is needed to pump the fluid.

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There are two types of dynamic pumps:

�� Centrifugal pumps are the most common pumps used for pumping water in industrial applications. Typically, more than 75% of the pumps installed in an industry are centrifugal pumps. For this reason, this pump is further described below.

�� Special effect pumps are particularly used for specialized conditions at an industrial site.

 

Brunton Compass

Brunton compass is a popular instrument used by geologists for surveying since ages. The instrument was invented in 1894 by Canadian mining engineer D. W. Brunton, and hence the name. Brunton compass was later commercially develped by Brunton, Inc. of Riverton, Wyoming . Today however, the name "Brunton compass" is referred to any type of pocket transit compass even if they are manufactured by other companies. Brunton compass, inspite of being expensive are considered indispensible tool for the structural geologist.

Components and sizes of Brunton compass:-

This compass is composed of delicate mirror and glass components which are vulnerable to shock and moisture thus, requiring care and periodic maintenance for proper application. Brunton compasses are available in a number of sizes which ranges from 8.5 cm(4 inches) in diameter and 5 cm thickness, 7cm(3 inches) in diameter and 4.5 cm thickness, 5cm(2 inches) in diameter and 4cm thickness. Brunton compasses have three main parts, box, sighting arm, and lid. The box contains most of the components: the needle; bull's eye level (round level to read horizontal angles); clinometer level (barrel-shaped) and clinometer scale (for reading vertical angles); damping mechanism (to more efficiently stabilizing the needle); lift pin (to lock the needle); side brass screw and index pin (to set and display the declination); graduated circle (to read the bearing). The needle has two ends: the north-seeking end (commonly white in genuine Brunton compasses, labeled 'N' in others), and the black, south-seeking end. The north-seeking end of the needle is pulled down in the northern hemisphere where the magnetic inclination is downward. An additional small weight attached to the south-seeking end of the needle provides proper balancing of the needle. The weight needs to be reversed if using the compass in the southern hemisphere where the magnetic inclination is upward.

The lid, attached to the box with a hinge, contains the mirror with the axial line and oval sighting window (for waist- and eye-level sighting), and the sight. The long sighting arm, attached to the box with a hinge, has a long, oval rectangular cutout or slot (for reading linear objects), and a tiltable sighting tip, which is used for aligning the line of sight. The circle card of the Brunton compass is designed in two traditional scales. The azimuth scale uses three digits, with north at 0⁰ or 360⁰, and south at 180⁰. The quadrant scale uses an alphanumeric notation (e.g., N60⁰ E, S20⁰ W) with the card graduated in four 90o quadrants (NE, SE, SW, NW); north and south lie at the two upper and lower 0⁰ marks, respectively.

The direction of a line on the ground is given by the bearing of the line, which is the horizontal angle between the line and a reference, commonly north in the quadrant scale, or 0⁰ (marked as 0⁰ on the card) in the azimuth scale. The reference, however, can also be the south (S) in the quadrant scale, when reading the bearing (i.e., trend) of south-trending linear objects. The position of 'E' and 'W' are reversed on the circular card; 'E' lies left of the 0⁰ mark and 'W' is to the right of the 0⁰ mark on the card. The reversal is designed to make the correct reading of the bearing possible. To appreciate this fact, notice that the north-seeking end of the needle always stays pointing north even when the compass dial is rotated. For example, to read a bearing of 45⁰, we level the dial and then turn right of north, but the north-seeking end of the needle turns to the left of 0⁰, which is actually east on the dial; so we read a correct bearing.
Uses and Importance of Brunton compass:-

Geologists use this as an instrument for measurement of the altitudes of structural features. This compass helps in the visualization of lines and planes in three-dimensional space. There is a natural sine scale on the cover of this compass for calculations of different readings during a survey.

Reflective readings from the dial are acquired by the mirror placed under the cover of the compass while the level inside this tells us when the base of the compass is horizontal. The lever stituated inside the compass helps in adjusting the levels. The entire mechanism allows measurements of dip angles.

The Brunton compass is commonly used for the following:

• Field mapping of geological objects since they provide a precise sighting-clinometer and hand level capability and can be used both at waist and eye levels.
• It is used in mapping and measurement of stratigraphic sections.
• It is used to measure azimuth (compass bearing).
• The compass is used in mapping and measurement of vertical angles, percent grade, slopes, inclination of objects, height of objects and for leveling.

The brunton compass has been the geologists most trusted tool and it is considered an ideal instrument for carrying out surveys. This is still the finest and most respected field instrument for geologists, surveyors, miners, civil engineers, environmental engineers and forestors world wide.

To determine the UCS of a given rock sample by Schmidt hammer.

Scope:-

To determine the UCS of a given sample to classify rocks.

Apparatus:-

• Schmidt hammer
• Rock specimen

Schmidt hammer:-

A Schmidt hammer, also known as a Swiss hammer or a rebound hammer, is a device to measure the elastic properties or strength of concrete or rock, mainly surface hardness and penetration resistance. The hammer measures the rebound of a spring loaded mass impacting against the surface of the sample. The steel hammer impacts the surface of a concrete with a steel plunger using a predetermined amount of energy and measures the distance that the hammer rebounds. This value is correlated to a compressive strength. The Schmidt rebound hammer is shown in. The hammer weighs about 1.8 kg  and is suitable for use both in a laboratory and in the field. A schematic cutaway view of the rebound hammer is shown in . The main components include the outer body, the plunger, the hammer mass, and the main spring. Other features include a latching mechanism that locks the hammer mass to the plunger rod and a sliding rider to measure the rebound of the hammer mass. The rebound distance is measured on an arbitrary scale marked from 10 to 100. The rebound distance is recorded as a “rebound number” corresponding to the position of the rider on the scale.

The Schmidt rebound hammer is shown in . The hammer weighs about 1.8 kg  and is suitable for use both in a laboratory and in the field. A schematic cutaway view of the rebound hammer is shown in . The main components include the outer body, the plunger, the hammer mass, and the main spring. Other features include a latching mechanism that locks the hammer mass to the plunger rod and a sliding rider to measure the rebound of the hammer mass. The rebound distance is measured on an arbitrary scale marked from 10 to 100. The rebound distance is recorded as a “rebound number” corresponding to the position of the rider on the scale.

Operational Principle:-

The rebound hammer test is based on the principle that the rebound of an elastic mass depends on the hardness of the surface against which the mass impinges. The Schmidt hammer consists of a spring-loaded piston which is released when the plunger is pressed against a surface. The impact of the piston onto the plunger transfers the energy to the material. The extent to which this energy is recovered depends on the hardness of the material, which is expressed as a percentage of the maximum stretched length of the key spring before the release of the piston to its length after the rebound.

Types of Schmidt hammer:-

There are different types of Schmidt hammer classified on the basis of several different energy ranges but often used are

• L Type Schmidt hammer
• N Type Schmidt hammer
• NR & LR Type Schmidt hammer

L Type Schmidt Hammer:-

Hammer is designed for testing thin-walled structural components with a thickness of less than 4" (100mm) or rock cores. This hammer features an impact of 0.74 Nm, 1/3 less energy than the Type N hammers. Include a conversion table with a (N/mm2) scale. L-type hammer has greater sensitivity in the lower range and gives better results when testing weak, porous and weathered rocks.

Type N Schmidt Hammer:-

Type N Hammer is designed for testing concrete items 4" (100mm) or more in thickness, or concrete with a maximum particle size less than or equal to

 

1.25" (32mm).It is designed for testing concrete within a compressive strength range ft-lbs (2.207 Nm).

Type NR & LR Schmidt Hammer:-

With this model Rebound values are recorded as a bar chart on a paper strip. One roll of paper strip offers room for 4000 test impacts.

APPLICATIONS:-

The hammer can be used in the horizontal, vertically overhead or vertically downward positions as well as at any intermediate angle, provided the hammer is perpendicular to the surface under test. The position of the mass relative to the vertical, however, affects the rebound number due to the action of gravity on the mass in the hammer. Thus the rebound number of a floor would be expected to be smaller than that of a soffit and inclined and vertical surfaces would yield intermediate results. Although a high rebound number represents concrete with a higher compressive strength than concrete with a low rebound number, the test is only useful if a correlation can be developed between the rebound number and concrete made with the same coarse aggregate as that being tested. Too much reliance should not be placed on the calibration curve supplied with the hammer since the manufacturer develops this curve using standard cube specimens and the mix used could be very different from the one being tested.

RANGE AND LIMITATIONS:-

1. Smoothness of the test surface:-

Hammer has to be used against a smooth surface, preferably a formed one. Open textured concrete cannot therefore be tested. If the surface is rough, e.g. a trowelled surface, it should be rubbed smooth with a carborundum stone.

2. Size, shape and rigidity of the specimen:-

If the concrete does not form part of a large mass any movement caused by the impact of the hammer will result in a reduction in the rebound number. In such cases the member has to be rigidly held or backed up by a heavy mass.

3. Age of the specimen:-

For equal strengths, higher rebound numbers are obtained with a 7 day old concrete than with a 28 day old. Therefore, when old concrete is to be tested in a structure a direct correlation is necessary between the rebound numbers and compressive strengths of cores taken from the structure. Rebound testing should not be carried out on low strength concrete at early ages or when the concrete strength is less than 7 MPa since the concrete surface could be damaged by the hammer.

4. Surface and internal moisture conditions of concrete:-

The rebound numbers are lower for well-cured air dried specimens than for the same specimens tested after being soaked in water and tested in the saturated surface dried conditions. Therefore, whenever the actual moisture condition of the field concrete or specimen is unknown, the surface should be pre-saturated for several hours before testing. A correlation curve for tests performed on saturated surface dried specimens should then be used to estimate the compressive strength.

5. Type of cement:-

High alumina cement can have a compressive strength 100% higher than the strength estimated using a correlation curve based on ordinary Portland cement. Also, super sulphated cement concrete can have strength 50% lower than ordinary Portland cement.

6. Carbonation of the concrete surface:-

In older concrete the carbonation depth can be several millimeters thick and, in extreme cases, up to 20 mm thick. In such cases the rebound numbers can be up to 50% higher than those obtained on an un-carbonated concrete surface.

Procedure:-

• Press the Schmidt hammer against a stone surface.
• At a given moment, the spring loaded mass is automatically impelled against the plunger and the rebound of the mass is indicated on the graduated scale by a pointer. The reading obtained is related to the initial tension of the spring and is called the Schmidt hardness number or Rebound number (R).
• As the result of each measure is dependent on the direction of the pressure exerted, the reading must be taken from the appropriate curve attached to each hammer to convert rebound in tension.

 

Precautions:-

• Hammer has to be used against a smooth surface, preferably a formed one. Open textured concrete cannot therefore be tested.
• When conducting the test the hammer should be held at right angles to the surface which in turn should be flat and smooth.

Comments:-

• It is a portable device and easy to handle.
• Being a portable it can be used to determine the in situ strength of the rocks.

 

To determine the slake durability index of given sample.

Scope:-

This test is intended to assess the resistance offered by a rock sample to weakening and disintegration when subjected to two standard cycles of drying and wetting.

Apparatus:-

The apparatus consists essentially of the following;

(a). A test drum comprising a 2.00 mm standard mesh cylinder of unobstructed length 100 mm and diameter 140 mm with solid fixed base. The drum must withstand a temperature of 105^oC. The drum has solid removable lid. The drum must be sufficiently strong to retain its shape during use, but neither the exterior of the mesh nor the interior of the drum should be obstructed, for example by reinforcing members.

(b). A trough to contain the test drum supported with axis horizontal in a manner allowing free rotation, capable to being filled with a slaking fluid such as water to a level 20 mm below the drum axis. The drum is mounted to allow 40 mm, unobstructed clearance between the trough and base of the mesh.

(c). A motor drive capable of rotating the drum at a speed of 20 rpm. The speed should be held constant to within 5 % for a period of 10 minutes.

(d). An oven capable of maintaining a temperature of 105^oC to within 3^oC for a period of at least 12 hours.

(e). A balance capable of weighing the drum plus sample to an accuracy of 0.5 g.

SLAKE DURABILITY TEST

This test method is used to estimate qualitatively the durability of weak rocks in the service environment.

Background: Rock properties change with time due to processes such as exfoliation, hydration, slaking, solution, oxidation, abrasion, etc.

Exfoliation: Rock being disintegrated sheet by sheet.

Hydration : Reaction with water.

Slaking: Weakening of rock due to repetition of wetting and drying.

Oxidation: Reaction with oxygen.

Abrasion: Smoothening of surface when scraped by other material.

Since these processes cannot be reproduced in the laboratory, resistance or rock (durability of rock) against them is evaluated in terms of some appropriate indices.

Slake Durability Test:-

A drum of 100mm in length and 140mm in diameter is rotated, half immersed in water, at 20 rounds per minute. The drum is made of a 2mm sieve. About 500g of rock is broken into 10 pieces and put in the drum. After rotation for 10 minutes, the percent of rock retained inside the drum, on a dry weight basic, is reported as the slake durability index, I_d (Goodman, 1980). A smaller I_d means that a greater amount of rock was broken into small pieces and lost through the sieve. 

Gambles' Slake Durability Classification (Goodman, 1980):-

Group Name	%Retained after one 10 min cycle (dry weight basis)	%Retained after two 10 min cycle (dry weight basis)
Very High Durability	> 99	> 98
High Durability	98 - 99	95 – 98
Medium High Durability	95 – 98	85 – 95
Medium Durability	85 – 95	60 – 85
Low Durability	60 – 85	30 – 60
Very Low Durability	< 60	< 30

                       (After Dr. I. Towhata, University of Tokyo)

Procedure:-

• A representative sample is selected comprising ten rock lumps each with a mass of 40-60 g. to give a total sample mass of 450-550 g . The maximum grain size of the rock should not be more than 3mm. Lumps should be roughly spherical in shape and corners should be rounded during preparation.
• The sample is placed in a clean drum and is dried to constant mass at a temperature of 105⁰C usually requiring from 2 to 6 hr in the oven. The mass A of the drum plus sample is recorded. The sample is then tested after cooling.
• Te lid is replaced, the drum mounted in the trough and coupled to the motor.
• The trough is filled with slaking fluid, usually tap water at 20⁰C to a level 20 mm below the drum axis and the drum rotated for 200 revolutions during a period of 10 minutes to an accuracy of 0.5 minutes.
• The drum is removed from the trough, the lid removed from the drum and the drum plus retained portion of the sample dried to constant mass at 105⁰C. The mass B of the drum plus retained portion of the sample is recorded after cooling.
• The drum is brushed clean and is mass D is recorded.

 

Geavity Separation Method and Jigging Machines

Gravity Separation Method :-

Gravity separation method is a traditional methods for treatment of tungsten, tin, gold ore, especially when dealing with gold dust, sand tin. In dealing with rare metals (niobium, tantalum, titanium, zirconium) of the placer application is also very common. Re-election is also used to sorting the weak magnetic iron ore, manganese ore.

The application of Gravity separation method:-

Gravity separation method is useful for re-election deal with the gangue minerals with large density difference between the ore and other raw materials. It is a effective way to dealing with Coarse-grained, medium-and fine-grained ore (generally limit is greater than 25 mm, 25 "2 mm, 2 ~ O.1 mm), but the efficiency is not high when in dealing with fine mineral mud (less than 0.1 mm), the flow of modern film processing equipment can be effectively recycled to the 20-30 micron grain size, centrifugal concentrator to 10 microns can be.

Gravity separation method in non-metallic mineral processing industry has also been developed in recent years, mainly used for treatment of asbestos, diamond, kaolin, apatite, pyrite and other minerals. In the election of copper, lead, zinc, antimony, mercury sulfide ore flotation plant, often used method of gravity concentration for primary election. Gravity separation method usually combined with other beneficiation process in the main election process, to select out the Concentrates or tailings in the state of Coarse-grained in advance.

This will help reduce production costs and metal loss. The Gravity separation method is always a priority, when there a variety of processing ore methods.

Gravity separation method must conduct in certain fluid media, Medium usually by water, Also use medium by air or heavy-medium (heavy liquid or dense medium). Media moved in a certain way inside separation equipment. Mineral grain begin loose with the effect of Medium buoyancy and hydrodynamic, and then to press the density (and sometimes by size) stratified. Layered mineral particles affect the nature of the process is its density, size, and minor shape factors.

Gravity separation method process method:-

There are several Gravity separation methods according to the Media campaign form and purpose of the job:

1) .Classification

(2) Heavy Media Beneficiation

(3) Jig Beneficiation

(4) Shaker Dressing

(5) Ore Chute

(6) Spiral Concentrator

(7) Centrifugal Dressing

(8) Wind Dressing

(9) Washing
Grading and washing operations are separated according to size, used in the preparation of the ore before enrollment. Other processes is substantial sorting operations, this is the following content will be described by this article.

The basic principle Gravity separation method:-

The essence of Gravity separation method can be summed up the separation process of loose – layered. Placed in Granular layer of ore in separation equipment.
Make a different density (or size) to switch a shift layered particles occurs, for re-election is to be achieved by density stratification. It begin to loose when drive by Fluid buoyancy, power or other mechanical forces, Purpose is to make a different density (or size) to switch a shift layered particles occurs, For Gravity separation method is to be achieved by density stratification.
Therefore, the role of fluid loose particles must the request of group stratification. This is the way to distinguish Gravity separation method from other two project of the Department. Fluid loose in different ways, the results of stratification is also affected.

The theory of gravity separation method, in short, it is about the relationship between Loose and layered. Stratified ore were discharged under the mechanical action; Stratified ore were discharged under the mechanical action. It can be considered is the condition of loose, layered is the goal, and the separation is the result, the method of gravity separation process that is the means to achieve this process

The work are controlled some basic principles such as
1. Settlement of particles and particle swarm theory
2. Particle group according to the theory of density stratification
3.Particle group in the slope flow separation theory　
There are also rotating flow in the sorting, although the media campaign in different ways. But in addition to differences in gravity and centrifugal force, the basic role of the law is still the same.

The theory about Stratified according to density swarm, Was first to start the study from the process of jigging。It has made a lot of jig stratification theory, and later appeared in a number of specialized vertical flow: the theory of stratification

Slope flow dressing was first in the thick layer of water over coarse ore processing, sorting is based on the particle velocity along the trough difference. After 1940， Slope to the stream beneficiation switch to the development of flow membrane dressing, Mainly used to sorting and micro-fine particles of ore fine. Fluid state divides into laminar flow and turbulent flow. That the turbulent fluctuating velocity is always loose bed of view of basic forces in laminar flow conditions, that is difficult to explain. 1954 R. A. Bai Genus (Bagn0ld) proposed interlaminar shear repulsion theory, Adds to this interesting theory on the blank.

However, as with the hierarchical theory，Inclined to rely on the existing flow of ore to make a reliable theoretical calculations is still difficult.

Although the theory of gravity separation to this day not reached the perfect point yet, but many of the processes and disciplines, as it already provides basic guidance for the production, and as similar to mathematical statistics and as the basis of the study and simulation.

Jigging Machines:-

Jigging machine belongs to gravity-based equipments, which can separate mineral based on differing of specific gravity. “Gandong” saw-tooth wave jig is mainly consist of three parts: main frame, driving set and jigging chamber.

Features:-The pulsing curve of the traditional jig is sinusoidal waveform, the up and down speed of water flow and acting time produced by the movement of membrane are almost same, so it is unfavorable to loose of jig bed and layering of minerals based on special gravity, and thus affect separation ability and recovery rate. Saw-tooth wave is an energy economy gravity equipment that is developed and improved from traditional jig on the basis theory of jig bed layering. Its jigging pulsating curve is similar to saw-tooth wave, which makes the up speed of water flow quicker than down speed of water flow, so it can improve looseness of jig bed and reduce suction action, which can lead to fully settlement of heavy particles in slurry, it highly improves separation ability and recovery rate. Stroke and frequency of stroke are adjustable.

Application:-Jigging machine is widely used in gravity concentration of tin, tungsten, placer gold, hematite ore, manganese, titanium, antimony, lead, tantalum, niobium and other minerals.

Shaking Table

Shaking Table:-

Shaking Table is a kind of mineral processing equipment of fine materials according to weight. It is widely used for distilling tungsten, tin, molybdenum, aluminum, zinc, other rare metal and noble metal ore, and it is also applicable for distilling iron, manganese and coal. The Shaking Table has the advantages of high enrichment grade, high separation efficiency, easy operation, convenient adjustment, and it can distill the final concentrate and gangue in one step, etc.

Vibration table is a kind of mineral processing equipment of fine materials according to weight. It is widely used for distilling tungsten, tin, molybdenum, aluminum, zinc, other rare metal and noble metal ore, and it is also applicable for distilling iron, manganese and coal. The rocking bed has the advantages of high enrichment grade, high separation efficiency, easy operation, convenient adjustment, and it can distill the final concentrate and gangue in one step, etc. 

Working Theory of vibration Table:-

The mineral processing of vibration Table is carried out on the rifle bed, the mineral particle cluster is fed from the upper corner of bed, and the water gullet provides horizontal current. The bed does asymmetry movement, so the inertial strength and friction are produced. Under the function of weight of mineral particle and horizontal current, the materials forms several layers according to weight and particle size, and do lengthways movement along the bed and horizontal movement along the oblique bed surface. Therefore, the mineral particle of different weight and fineness flow down in the shape of sector along the catercorner lines, and are discharged through the concentrate and gangue terminal zones. Finally, the concentrate, mineral and gangue are separated.

Performance and Feature:-

The Shaking Table has the advantages of good separation capacity, stable performance, high efficiency, smooth, lower noise, easy operation and maintenance, etc.