Title of Invention

A PROCESS FOR THE MANUFACTURE OF SUPER POZZOLAN FROM ASH (INCLUDING FLY ASH) OBTAINED BY THE COMBUSTION OF COAL OR COKE AND SUPER POZZOLAN OBTAINED BY THE SAID PROCESS

Abstract A process for the manufacture of super pozzolan from ash (including flyash) obtained by the combustion of coal or coke comprisesg the steps of separating the silica and alumina present as phase A in the said ash from the silica and alumina present as reactive phase B in the said ash, by separation means, such as (i) air classification (ii) hydro-cycloning (iii) flotation (iv) sieving. The separated reactive phase B so obtained is ground, if necessary, to a fineness necessary for rendering the said reactive phase B super pozzolanic.
Full Text This invention relates to a process for the nanufacture of super pozzolan from ash (including flyash) obtained by the combustion of coal or coke. The invention also relates to super, pozzolan manufactured by - the said process.
■4-
Hydraulic cement is a product which hardens and attains strength in the presence of moisture to render a water impervious hard mass.
Ash ■(including flyash) obtained from coal/coke combustion, slag, silica fume, rice husk ash (RHA) are some of the industrial by-products identified as complementary cementing materials. In this lot, while slag is cementitious in behaviour, ash from coal/coke combustion, silica fume and rice husk ash are pozzolanic in performance which means that these products attain activity in the presence of lime to render mineralogy akin to that of ordinary portland cement (OPC).
Ash from coal/coke combustion could be both pozzolanic and cementitious as identified in ASTM C 618. Ash with

less than 10% lime is identified as Class F (ash obtained by the combustion of bituminous coal or coke) and pozzolanic whereas ash with more than 10% lime is categorized as Class c (ash obtained by the combustion of lignite or sub-bituminous qoal or coke) and is cementitious.
Silica fume and RHA are categorized as super pozzolans, for having reactive phases at more than 80% - 90% as against approximately 10% - 50% in other pozzolans, which can initiate high early strength in cement mortar and concrete.
According to the prior art, ash is added to OPC as complementary cement input and the resultant product is specified as portland pozzolan cement (PPC) as in BIS 1489 (I) - 1991. PPC is yet to win the consumers" confidence in India. As a matter of fact, PPC is banned for structural applications by certain Government Departments in India owing to some structural failures experienced during the 1980"s by those who used substandard pozzolans. However, the upgradation of thermal plant operations has invariably improved the quality of flyash. Electrostatic precipitators (ESP) installed at thermal plants for

pollution control have, in turn, facilitated the collection of flyash at different fineness.
«*" ■ Despite the improvement in the quality of flyash and, in turn, that of PPC, the latter is preferred in India only next to OPC, particularly, from early strength point of view. For this matter all blended cement such as Portland slag cement (PSC), PPC etc. are noted for their slow rheology and low strength at early ages.
In countries with advanced concrete technology practices, this problem is offset through the deployment of chemical admixtures such as super plasticisers where the anomalies in early strength are corrected by physical means, that is, by bringing a change in water cement ratio (w/c). Adding super pozzolan such as silica fume to cement though increases w/c ratio, early strengths are attained, more than the characteristic strengths, by virtue of chemical reactions and resultant rapid formation of mineralogy. Such increase of early strength is in the order of 10% to 35%.
However silica fume being the popularly used super

pozzolan world over, considerable pressure is acting on the product making it dearer in the international market. This has necessitated research on alternative super pozzolans. RHA is one such development with proven technology and engineering data.
Against the need for super pozzolans, this invention proposes a process for manufacturing the same from ash (including flyash) obtained by the combustion of coal/coke.
The known super pozzolans in vogue are silica fume and RHA, whose reactive phases are totally constituted by amorphous silica.
This invention relates to a process and product pertaining to super pozzolan containing predominantly the glasses of alumino-silicates. The super pozzolanic character is attributed to the contribution to early strength of hydraulic cement mortar and concrete by about 10% - 35% without any chemical admixtures.
This invention involves a process of manufacture and product manufactured from fly ash and other ash of fuel

combustion such as coal, coke whereby the product behaves as super pozzolan to improve the early strengths of mortars and concretes of hydraulic cements such as OPC, PPC, PSC, or any other non-conventional cements of similar behaviours such as FaL-G, belite cement and the like.
This invention converts normal pozzolans into super pozaolans whereof the latter can increase the early strength of hydraulic cement, mortars or concretes, as achieved by other super pozzolans, such as, silica fume, RHA and the like at suitable dosing parameters.
This invention pertains to a super pozzolan that can be used as a substitute for silica fume, RHA and the like to render early strength to mortars, and concretes manufactured out of hydraulic cement such as OPC, PPC, PSC or any other non-conventional cements of similar behaviour such as FaL-G, belite cement and the like.
Ash obtained by the combustion of coal or coke has two phases: a non-reactive phase (herein also called phase A) and a reactive phase (herein also called phase B). Phase A contains crystalline silica and alumina. On the other hand phase B contains silica and alumina in

glassy and/or amorphous form.
Phase B also contains crystalline calcium compounds such as one or more of calcium silicates, calcium aluminates, calcium alumino -sulphates and calcium sulphates in the case of ash obtained by the combustion of lignite or sub- bituminous coal or coke.
The process, according to this invention, for the manufacture of super pozzolan from ash (including flyash) obtained by the combustion of coal or coke comprises the steps of separating the silica and alumina present in phase A in the said ash from the silica and alumina present as reactive phase B in the said ash , by separation means , such as (i) air classification (ii) hydro - cycloning (iii) flotation (iv) sieving ; and grinding the separated reactive phase B so obtained, to a finenes necessary for rendering the said reactive phase B super pozzolanic.
EXAMPLE
Ash is obtained by the combustion of bituminous coal in boilers. This ash has two components : a non - reactive phase A of 60% to 90% by weight and a reactive phase

(B) of 10% to 40% by weight. The non-reactive phase component contains silica and alumina in the crystalline phase and the reactive component contains silica and alumina in the glassy and/or amorphous phase.
These phases are separated by air classification.
The separated phase B is then ground, if necessary, to fineness 7500 sq.cm. blaine specific surface area to obtain super pozzolan.
The preferred range of fineness is 6000 - 12,000 blaine specific surface area.
The terras and expressions in this specification are used to describe and illustrate, but not to limit the scope and ambit of this invention.


We Claim:
1. A process for the manufacture of super pozzolan from ash (including
flyash) obtained by the combustion of coal or coke comprising the steps of
separating the silica and alumina presen diphase A in the said ash from the
silica and alumina present as reactive phase B in the said ash, by separation
means , such as (i) air classification (ii) hydro - cycloning (iii) flotation (iv)
sieving ; and grinding the separated reactive phase B so obtained, to a
fineness necessary for rendering the said reactive phase B super pozzolanic.
2. A process as claimed in Claim 1 wherein the phase A contains crystalline
silica and alumina.
3. A process as claimed in Claim 1 or Claim 2 wherein the reactive phase B
contains glassy and/or amorphous silica and alumina.
4. A process as claimed in any one of the preceding Claims wherein the
reactive phase B is ground to fineness 6000 - 12000 sq. cm. /gm. blaine
specific surface area.

5. A process for the manufacture of super pozzolan
from ash (including flyash) obtained by the combustion
of coal or coke substantially as herein described with
and illustrated.
6. Super-pozzolan whenever manufactured by a
process as claimed in any one of the preceding Claims

Documents:

0044-mas-2000 abstract duplicate.pdf

0044-mas-2000 abstract.pdf

0044-mas-2000 claims duplicate.pdf

0044-mas-2000 claims.pdf

0044-mas-2000 correspondence-others.pdf

0044-mas-2000 correspondence-po.pdf

0044-mas-2000 description (complete) duplicate.pdf

0044-mas-2000 description (complete).pdf

0044-mas-2000 form-1.pdf

0044-mas-2000 form-19.pdf

0044-mas-2000 form-26.pdf


Patent Number 216196
Indian Patent Application Number 44/MAS/2000
PG Journal Number 13/2008
Publication Date 31-Mar-2008
Grant Date 10-Mar-2008
Date of Filing 20-Jan-2000
Name of Patentee MADRAS CEMENTS LIMITED
Applicant Address AURAS CORPORATE CENTRE, 98-A DR. RADHAKRISHNAN ROAD, MYLAPORE, CHENNAI - 600 004,
Inventors:
# Inventor's Name Inventor's Address
1 NATERI KALIDAS FAL-G MANISON, 35 SHRI VENKATESWARA COLONY, SHEILANAGAR, VISAKHAPATNAM 530 012,
2 NATERI BHANUMATHIDAS FAL-G MANISON, 35 SHRI VENKATESWARA COLONY, SHEILANAGAR, VISAKHAPATNAM 530 012,
PCT International Classification Number C04B 18/06
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA