1.1 Portland cement
The process of
manufacturing Portland cement has passed through various stages of development
since prototype of today’s Portland cement was invented by Joseph Aspdin in
1824. The furnace used by him was a dome kiln of approximately 11m in height
and 5m in diameter with a production of approximately 15tons per charge. It
took several days to produce each charge. To meet growing demand in the
following years, long wet and dry process kilns were installed. Later on, these
kilns gave rise to suspension preheater kilns and then in early seventies to
precalcination technology. These developments have finally resulted in more
production capacity for the same volume of kiln. With preheater kilns, the
capacities couldn’t be reached beyond 4500 t/d, owing to the limitations of
higher thermal load in the burning zone. Precalciner kilns are now in operation
in various countries, producing more than 10,000 t/d of clinker.
The cement manufacturing
process is an energy-intensive process. A substantial amount of thermal energy
is needed in its processing and electrical energy is considerable consumed in
the grinding of raw materials and clinker. The cost of thermal and electrical
energy alone accounts for the major cost of cement production. The
production of one ton of cement clinker requires the combustion of about 80-90
liters of heavy oil or 80-100 cubic meters of natural gas or 130-150 kilograms
of coal. An average electric energy consumption for one ton of cement produced
in a suspension preheater/precalciner kiln is 100-105 kWh, though power ranging
from 80 to 85 and even 70 kWh is possible with the latest efficient equipment
and machinery. A specific fuel consumption of 680-700 kcal/kg of clinker is
being achieved as against 1400-1500 kcal/kg of clinker in the earlier wet
kilns.
Cement industry is a dynamic industry
and the entire manufacturing process is undergoing highly technology
advancement. The use of pre-grinders, vertical mills, two support kilns having
provision of a friction drive in place of gear and pinion drive, 5/6 stage
preheater kiln system with efficient pre-calciners and new generation of
clinker cooler having heat recuperating efficiency of about 80% or more shall
dominate in future.
In the new millennium, a strong trend
will undoubtedly be the replacement of conventional fossil fuels by waste
materials with residual heat content including hazardous. Also the subject
matter of environmental management and the reduction of the amount of CO2
generated per ton of cement by using additives in cement will be intensified.
By adopting clean production technology, cement plants hitherto considered as
dirty and difficult would be acknowledge as clean and comfortable in the years
to come.
1.1.1 Manufacturing Process
The manufacturing of Portland cement
starts with the mining or quarrying of the raw materials. To reduce raw mix
variations, the larger size materials received at the plant are crushed,
homogenized and ground to secure a uniform bled for proper reaction. An
intimate mixture usually of limestone and clay or other suitable materials is
sintered in a kiln at a temperature of 1450-1500 degree centigrade for a
certain time. Pulverized coal, fuel oil or natural gas along or in combination
with waste derived fuel is introduced in its front end for combustion. This
product called clinker after cooling ground with 4-6% of gypsum or other form
of calcium sulphate. Some specifications allow the addition of other materials
during grinding of clinker. The cement is then stored in silos for shipment in
bags or in bulk.
1.1.2 Process automation
Process automation has been achieved by
combining traditional engineering skills with technological innovation.
Reliable control programs have been developed which offer comprehensive plant –
wide control of cement manufacturing operation such as quarrying, grinding ,
kiln operations, dispatch and production scheduling etc. PLC installed monitors
the measured values as well as those of closed –loop control. Standard software
packages are available for the control of variable of technological process.
Advances in computer technology have
greatly enhanced the scope and performance of expert systems. The controllers,
indicator and recorders of process variables and CCTV monitors the clinker
production and reduces the burden of operators while guaranteeing economical
production and the quality of the final product. Such systems have resulted in
significant improvements in kiln stability, fuel efficiency, and clinker
quality and production quantity.
An on- line X-ray fluorescence
spectrometer with automatic sampling and transporting system from various
stages of manufacturing guarantees continuous testing of the kiln feed and thus
ensuring smooth pyro processing of clinker in the kiln. In the recent years, a
concept of very extensive automation by installing a central robot has emerged
and is being adopted to ensure a consistent quality control over the entire
process of cement manufacturing.
Needless to say, the best equipment in
the world will not perform like the best unless the persons in charge of
operating them know what they are doing. Automation also need a lot of training
and education to handle the sophisticated system involved. Integrated
engineering with common database, standardization and pre-defined modules are
being developed for optimum production and engineering planning.
1.2 Cement Production in Nepal
The use
of cement in Nepal as binding material came into effect from the beginning of
early 1950s. Early users of cement were dependent on imports from India to meet
their needs. The history of cement industry in Nepal dates back to 1970 when
Himal cement factory established. Later with peaking demand of cement as
urbanization was in its initial phase, under financial assistance of Japanese
Govt., Udayapur Cement Industries Ltd. was established on 31st
Jestha, 2044 B.S (14th June 1987 AD).
The OPC
or the Ordinary Portland Cement is the only type of cement being produced in
Nepal. This is most commonly being used in simple construction like building
house etc. It is a fine powder produced by grinding Portland cement clinker
(more than 90%), a limited amount of calcium sulfate (which controls the set
time) and up to 5% minor constituents (as allowed by various standards). There
are three major and largest cement industries in Nepal which produce their own
clinker.
1.
Hetauda Cement
Industries Ltd., Lamshure, Hetauda
2.
Udayapur Cement
Industries Ltd., Jaljale, Udayapur
3.
Shree Maruti Cement
Ltd., Mirchaiyaa
1.3 Brief Summary of the industry
Udayapur Cement
Industries Ltd. is the government undertaking industries established on 31st
Jestha, 2044 under the companies ACT 2021. The plant was jointly financed by
Government of Japan and Government of Nepal. Out of total investment 18.77
Crore Japanese Yen was from OECF Japan grant and rest 44.38 Crore was financed
by GoN. The construction work of plant was started on 2046 by Kawasaki Heavy
Industry Japan and commercial production was started from Magh 2049 with
277,000 MT of cement per year. The industry is producing high quality Ordinary
Portland cement in its brand name ‘Gaida Chap’ and it is currently providing
employment opportunities to more than 500 people including local and non-local
people.
The plant is
located in Jaljale -11, Udayapur, Nepal. It is about 7 KM west from Gaighat
which is District Administrative Office of Udaypur and 22 KM north from
Mahendra Highway. Again, it is about 225 KM and 125 KM from Birgunj Custom
Point and Biratnagar Custom Point respectively. In case of import, the Indian
suppliers quote their price inclusive of transportation up to custom point.
The plant location
is situated in the area where there are no cement industries in 50 KM
surrounding area and meeting local demand is strength. However, the cement
produced by the industry is highly demanded by the consumers all over the
Nepal. At proposed production capacity i.e. 60% of installed capacity, there is
no need incurring any additional marketing cost due to trustworthiness of
consumers as well as quality of the cement produced.
The plant location has been set up in
the area having adequate basic physical infrastructure such as road, water,
electricity and availability of the labor and raw materials.
1.3.1 Brief Information of the company
Locations
Quarry site: Sindali, Jalpa-Chilaune VDC, Udayapur district
Plant site: Jaljale, Triyuga Municiplity-11, Udayapur
district
Objective: Production and distribution of OPC cement
Establishment: 2046 B.S/ 1989 A.D
Construction Period: Bhadra 2046 – Ashwin 2049
Sept.
1989 – Oct. 1992
Commercial Prod. : Magh, 2049 / Jan. 1993
Inauguration: 2052 B.S / 1995 A.D
Company Reg. No: 164/043/44
Financial
Assistance for its establishment
OECF Japan : ¥ 18,770 Million
Equity Share of Govt. of Nepal : NRs. 450 Million
Project
Implementation
Mode :
Full Turnkey Basis
Consultant : Onoda Engineering &
Consulting Company Ltd., Japan
Contractor : Consortium of Kawasaki
Heavy Industries Ltd. &
Tomen Corporation, Japan
Production
Capacity per Day
Clinker Production : 800 Metric. Tons
Cement Sales : 16,800 Bags
Annual
Requirement of Raw Materials
Limestone : 330,000 M.T
Clay :
57,000 – 82,500 M.T
Silica Sand : up to 21,000 M.T
(Currently not in use)
Iron Ore : 4,000 M.T
Gypsum :
10,500 M.T
Sources
of Principal Raw Materials and Fuels
Limestone : From own mine (located 27 Km away –
transported via ropeway)
Deposits enough for more than 200 years
continuous production.
Clay :
Own source
Silica Sand : Own source
Iron Ore : Import/ Purchase from vendors
--------à NRs. 15,000 per M.T
Non-coking coal : Import/ Purchase from vendors -------- à
NRs. 16,000 per M.T
Gypsum :
Import/ Purchase from vendors ---------à NRs. 7,770 per
M.T
Furnace Oil/ Diesel : Nepal Oil Corporation
------------------à NRs. 1, 00,000 per KL
Cement Bag/ Sag : Purchase from vendors as per order ---à
NRs. 20 per pcs.