FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
THE PATENTS RULES 2003
Complete Specification
[See section 10, rule 13]
TITLE OF THE INVENTION: "A METHOD FOR PRODUCING ROCK CRUSHED SAND"
APPLICANTS:
BHARUCHA STONE AND SAND WORKS PVT. LTD
"Kutika"31/l Pune-Solapur Road,
Pune 411013
India
The following specification particularly describes the invention and the manner in which it is to be performed:

FIELD OF THE INVENTION
The present invention relates to a process for preparing Rock crushed sand. It proposes the production of well graded fine sand by involving three stages of crushing process.
BACKGROUND OF THE INVENTION
River Sand is very important natural resource and plays an important role in construction industry. Good quality of sand is required to produce good quality of concrete and plaster surface on wall.
Good quality sands should have following characteristics:
1. It has to be totally dry
2. It is to be screened through 4.75m (3/16) sieve.
3. Adequate quality of it (40 to 50 %) should pass through micron sieve (BS 25).
4. In old terminology fineness modulus should be in range of 2.6 to 2.9.
5. It should be free of harmful material such as clay, stilt (not exceeding 3% by weight or 8% by volume i.e. fines passing through 75 micron sieve).
6. It should be totally salt free.
Sand not having above characteristic has to be site modified to have above characteristic.
The natural river sand is the cheapest resources of sand. River sand is not much preferred for concrete preparation because of its poor quality and contains mud and silt. Shortage of river sand is also a biggest problem now days. The places which are far from rivers cannot have river sand easily or getting river sand is not very economical there. However the excessive mining of river bed to meet the increasing demand of sand has created ecological problem. These are some of the problem which gives rise to find an alternate way to produce good sand suitable for construction work and rock crushed sand is a good alternate of river sand

SUMMARY
The embodiment of the present invention contemplates a method for preparing sand form rock comprising the following steps;
first of all breaking large rocks into smaller ones then selecting small rock particles which are used as feed material. Rock particles are mainly the ground particles.
The feed material undergoes treatment in centrifuge under high rotor speed. Centrifuge consists of rock lined rotor operating at a high rotor speed. The treatment causes breakage in the particles and removes the irregularities resulting in production of small smooth particles. Breakage is mainly due to the high intensity inter-particle and particle-to-rock lining collision.
Smooth particles discharge out and then have to be collectively screened and segregated to form fine graded sand particles.
The advantage of the present invention is that it produces fine quality of graded sand. The crushed sand has required correct grading that produces excellent concrete and plaster using most economical mix. The crushed sand produced with low FM is most ideal for plaster work. When this plaster sand is used, end user gains substantial benefits as no screening at site is required (i.e. no wastage as in river sand ) and no silt and deleterious material in it. Also continuous supply is ensured since it is machine made. The crushed sand holds advantages over river sand. Table 1 shows comparison between river sand and crushed sand.
Table-1
Type of Sand ' River Sand Crushed Sand
Cement(Gde 43) 50 Kg 50 kg
20"mm coarse aggregate 120 140kg(Rounded
kg(flaky) irregular)
10 mm coarse aggregate 50 kg (flaky) 45 kg(Rounded
irregular)
Sand 96 Kg 120 Kg

Water 25 Lrr 25 Ltr
Avg. 6 inches cube weight(after 28 days curing) 8.1 Kg 8.67
Density of Concrete 2,400 Kg/m3 2,571 kg/m3
Crushing strength 7 days 26.45 kg/cm 30.23 kg/cm2
Saving of cement (without violating IS 456-2000 Codal 0.7 bag/m3 provision)
Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 shows the basic working mechanism of method.
Figure 2 shows the graphical representation of various controllable variables affecting the method.
Figure 3 shows the height adjustment to eliminate erratic feed or restricted flow.
DETAILED DISCLOSURE
The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. The following discussion assumes the reader is familiar with concrete, rotor machine, basic crusher mechanism and basic nuances of construction industry.
The method disclosed uses three stages of crushing in which the final stage uses rock on rock crusher and a rock lined rotor that work at a higher velocity, dry stone pump hurling a continuous

rock stream into a stone lined crushing chamber. (Figure 1) Material fed into the top of the machine is accelerated in the rock lined rotor, achieving higher velocities. The rotor continuously discharges into the crushing chamber. This process replenished the rock lining, while at the same time maintains a rock on rock chain reaction of crushing and grinding. Rock particle is fed into the top of the machine and splits into two streams; one flow directly into rotor and another flow as cascade. The material flow fraction is controlled by means of a hydraulic cascade choke adjuster which restricts the amount of materia] entering the rotor and forces excess material to cascade into the crushing chamber, directly in the line of the crushing action.
Feed material passing through the control plate opening flows into the rock-lined rotor via a feed tube and is accelerated horizontally outwards into a rock-lined crushing chamber. Material is continuously discharged and recombines with the cascade material entering the crushing chamber. Size reduction is accomplished in the crushing chamber primarily by rock on rock impact, attrition and abrasion. Crushed material falls out of the crushing chamber into the base and down through discharge chutes to exit from the bottom of the crusher.
The machine offers a number of controllable variables which effect the final product grading as follows (Figure 2)
Rotor Speed: Increasing rotor speed increases the particle kinetic energy and increases the reduction in particle size in sand. Thus sand grading can be controlled.
Cascade: Increasing the cascade flow decreases the reduction ratio achieved whilst increasing the capacity of the crusher. Thus increases machine output per hour.
Feed Gradation: Changing the size distribution of the feed to the machine will effect the size distribution of the crushed sand product. It controls FM of sand.
Screen Aperture: When operating in closed circuit the final product sand is produced by screening the product and is controlled by the screen aperture and screening method It helps in producing good plaster sand.
To eliminate erratic feed or restricted flow, adjustment of the height of the feed spreader plate will be required. This simple adjustment of height provides a vortex flow that eliminates the

weight of material which with some feed gradations and same combinations causes the stalling of the flow through the control gate opening. (Figure 3)
As can be seen above the method of making sand is highly specialized function using machinery arid screening process that is very sophisticated and has to be controlled very rigorously Sand produced in the plant is daily tested for its stringent standards and any changes required are made in machinery to maintain the quality.
Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present disclosure can be implemented in a variety of forms. Therefore, while this disclosure has been described in connection with particular examples thereof, the true scope of the disclosure should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, specification, and the following claims

Claim
1. A method for preparing sand form rock comprising the steps as orders;
Breaking large rocks into smaller particles in two stages and choosing small rock
particles used as feed material;
said feed material undergo treatment in centrifuge under high rotor speed;
said treatment causes fracture in particles and chip away irregularities resulting in
production of minutes rounded cubical particles;
said rounded cubical particles discharges and are further graded in a screening process
to form as fine graded sand.
2. The method as claimed in claim 1, where in the small rock particle comprises of ground
materials.
3. The method as claimed in claim 1, where in the centrifuge consist of rock lined rotor
operation at a high rotor speed.
4. The method as claimed in claim 1, where in feed material is washed prior entering into
centrifuge.
5. The method as claimed in claim 1, where in the said fracture mechanism is due to the
high intensity inter-particle and particle-to-rock lining collision.
6. The method as claimed in claim 1 where the final product (fine graded sand) is obtained
by screening process to grade the rounded cubical particles into the gradation required to
form fine sand.