WO2010126457A2

WO2010126457A2 - High performance cement and production process

Info

Publication number: WO2010126457A2
Application number: PCT/TR2010/000088
Authority: WO
Inventors: Cengiz Koca
Original assignee: Cengiz Koca
Priority date: 2009-04-29
Filing date: 2010-04-28
Publication date: 2010-11-04
Also published as: WO2010126457A3; CN102405197A; EP2424825A2; RU2011148083A; TR200903373A2

Abstract

This invention is related to the production of High Performance Cement (HPC) where the clinker (being the raw material for ordinary Portland cement (OPC) which is the major material in the construction industry), is ground through a special grinding technology (regarding conformity to the designated principles during grinding, like; regime temperature, humidity, grinding duration) by adding a modifier (complex chemical composition) for improving mechanical-chemical properties of the cement particles, resulting production of high performance cements such as HPC 62.5 with better properties than the known cements in the standards. The invention is also related to the use of same technology to improve the performance and quality of the composite cement types with reduced clinker content for replacement of other additions such as; slag, limestone, sand, fly ash, trass (pozzolan) etc. The invention also defines the production process and production units of the high performance cement.

Description

HIGH PERFORMANCE CEMENT AND PRODUCTION PROCESS

Technical Field

This invention is related to the production of High Performance Cement (HPC) where the clinker being the raw material for ordinary Portland cement (OPC) which is the major material in the construction sector, ground through a special grinding technology (regarding conformity to the designated principles during grinding, such as; regime temperature, humidity, grinding duration) by adding a modifier (Complex chemical composition) resulting improvement in mechanical- chemical properties of the cement particles produced. The invention is also related to the use of same technology to improve the performance and quality of all composite cement types other than pure Portland cement. The Invention also defines the production process and production units of the High Performance Cement, besides the use of modifier.

Related Art

Production of the cement used in the construction sector for over hundred years consists of two major stages. These are; production of clinker from the ground mixture of related raw materials after crushing and homogenization and grinding of clinker produced together with the gypsum and sometimes also by adding some other minerals.

The main raw materials for cement production are, lime stone and clay, where the other constituents may be sand, bauxite, pyrite ash and iron ore. Clinker composition, resulting from production process of clinker as main product, contains calcium oxide, silisium oxide, aluminum oxide and iron oxide.

In the literature, there are various patent applications related to the cement compositions. For example; in the patent with the publication number EP1451126, the description is given for a new slurry cement composition for the construction sector. Patent application with the number of WO9711132 defines improved dry shrinkage cement composition. On the other hand, patent application with the publication number TR 200301984 defines cement which contains silicoferrochrome slag and CO₂ additive and is durable and flexible cement.

The cement (Portland cement) produced under known technologies are classified based on different raw material composition like, Turkish Standards TS ENV 197-2; and equivalent

European standards EN 197-2, 2000 EQV-; BS EN 197-2--; NF P15-101 -2-; DIN EN 197-2--;

EN 197-2.2000 EQV-; as well classified based on three types of strength, namely PC 32.5, PC

42.5, PC 52.5.

Among above mentioned cements, PC 32.5 relates to 32.5 N/mm², PC 42.5 relates to 42.5

N/mm² and rarely produced PC 52.5 relates to 52.5 N/mm² due to its expensiveness.

Furthermore in different ratios, TC is produced using trass (pozzolan), SC is produced using slag, FAC is produced using fly ash where their strength classes are 32.5 N/mm² and 42.5 N/mm² (see Table 1 General Types of Cement).

Table 1 General Types of Cement

Since, cements produced under known technologies do not directly provide required high strengths, workability and lower water cement ratio in concrete; production of high strength concrete becomes difficult, resulting strength restrictions leading to non economical concrete sections in high concrete structures.

The required economic life of the concrete can not be long enough due to non achievement of the durability and/or strength quality of the concrete against various environmental conditions. As a result, it is aimed to develop a production technology aiming to produce high performance cement, by improving the properties of the cement produced with known technologies.

The Purpose of the Invention

In consideration, the current level of known cement production technique, the primary purpose of the invention is to produce High Performance Cement (HPC) as a result of developed production technology and using modifier, which provides reduction of water/cement ratio, increase compressive strengths for early (24 hours) and final (28 days) periods and improve basic properties like impermeability, non-shrinkage and non-cracking in concrete production. Other purpose of the invention is to prevent strength loses and increase the performance of cements resulting from replacement of limestone, trass (pozzolan) which are easy to extract in nature and/or industrial wastes like blast furnace slag, fly ash with clinker in order to reduce its content in cement production due to concerns related to cost and environmental pollution. Using HPC results the following improvements in concrete performance:

- early strength up to 300 kg/cm² in 24 hours, and 500 kg/cm² in 48 hours,

- high strength up to 1200 kg/cm² in 28 days,

- extended life time due to high performance,

- usually early removal of formwork without any steam cure application,

- high abrasion resistance,

- easy workmanship for concrete placing in sophisticated forms due to high workability concrete,

- reduction in sections of structural concrete elements due to high strength, resulting less structural mass against earthquake effect,

- lower water cement ratio to provide higher resistance to frost in winter,

- preventing corrosion and achievement of high adherence and impermeability due to filing all capillary gaps in the concrete.

The invention developed for the purpose defined here above is the production process of High Performance Cement to be used as a structural material in construction industry, and it consists of the following process steps:

- placing of the all raw materials, which shall be Portland clinker, gypsum and additives for composite cement production such as limestone, slag, sand, trass (pozzolan) etc., into the feeding bunker (1) for production of HPC depending on defined cement quality and classes,

- automatic dozing of raw materials as per required using belt scales placed under the feeding bunkers,

- measuring of the raw materials on the weighing belt scales, comparing the actual flow and the programmed flow by monitoring the speed of the weighing belt scales and re-adjusting the speed of the weighing belt scales accordingly, - dedusting of the raw materials by placing a suitable filter above the weighing belt scales,

- transfer of the raw materials to the feeding conveyor of the first mill,

- feeding of the raw materials from the conveyor to the first ball mill for coarse grinding less than 500 microns,

- suction of the semi-ground material by the filter above the mill and transfer to the elevator through the air slides,

- feeding of the coarse ground material to the second ball mill by the elevator and also feeding of the modifier with a determined ratio to clinker quantity from the modifier silo, and fine grinding at any range from 3,500 to 9,500 blaine as per the type of the end product,

- suction of the finished product named as High Performance Cement by filter at the exit of the second ball mill and transferring to the elevator by air slide,

- transferring of High Performance Cement to the air swept separator from the elevator,

- the separation of fine cement to the required particle size and transferring to the elevator by the air slide, and

- transferring the cement to the silos from the elevator by the cement handling units.

One preferred application of the invention is returning the cement particles, which are separated by the separator and not ground to the required fineness, back to the second ball mill through the air slides for re-grinding.

Another preferred application of the Invention is feeding of the modifier from the modifier silo to the second ball mill by modifier feeding unit, in the ratio of the raw material passing through the raw material conveyor band of first mill.

Another preferred application of the invention is fineness control of the end product by placing control valves and pressure gauges for adjustment of valve openings to increase or decrease the flow.

Another preferred application of the high performance cement (HPC) invention is the achievement of keeping the water cement ratio of the concrete and mortars below 45 % without using any other concrete additives.

For the achievement of purpose defined, High Performance Cement (HPC) is developed through the process as detailed above, which contains modifier in variable ratios (0.5% - 2%) with respect to the raw material properties and especially the clinker content.

For the achievement of purpose defined, performance of cements are developed through the process as detailed above, which contains various high content constituent materials such as limestone, slag, gypsum, trass (pozzolan) etc, for the purpose of reducing the Portland clinker content. The principals and basic characteristic properties of the Invention and its advantages are defined with below diagrams and the referred explanations, therefore evaluation of the Invention should be done in consideration of such for better understanding.

Description of the Figures

Figure-1 : Schematic diagram of the High Performance Cement production plant.

References:

1 Feeding Bunker 16 Separator

2 Weighing belt scales 17 Elevator

3 Feeding conveyor of first mill 18 Filter

4 Filter 19 Transfer units

5 Filter 20 Silo

6 First ball mill 21 Silo

7 Air slide 22 Elevator

8 Modifier silo 23 Filter

9 Modifier feeding unit 24 Screen

10 Elevator 25 Bunker

11 Modifier feeding belt 26 Bag filling station

12 Second ball mill 27 Screw

13 Air slide 28 Vehicle for bagged cement

14 Filter 29 Vehicle for bulk cement

15 Elevator

Detailed Description of the Invention

This invention is related to the production of High Performance Cement (HPC) in order to improve dispersion and reaction capability of normal Portland clinker to be used as structural construction material; by adding the modifier and using the special grinding technology (regarding conformity to the designated principles while grinding, such as; regime temperature, humidity, grinding duration). Invention is also related to the production process and production units of High Performance Cement (HPC).

During the production of the subject High Performance Cement (HPC), the primary raw materials shall be Portland clinker, gypsum and the modifier with a certain ratio of the clinker content. Although, any clinker could be used for HPC production the percentage of modifier shall change depending on chemical properties and quality of clinker used. The invention provides improvement of chemical and mechanical properties of the cement particles which provides reduction in water demand of the cement, resulting early as well as high strength for concrete besides high performance.

The High Performance Cement (HPC) shall be classified similar to the other cement classes with respect to the strength class and raw material composition and named as in the range of

HPC 62.5 to HPC 82.5 where such designations do not take place in the existing cement standards.

The letter Η" is used to represent high performance for the application of the Invention to the composite cements defined in the existing cement standards. HPC 62.5R is detailed as an example for description of the Invention.

Schematic diagram of the production plant for High Performance Cement is given in Diagram-1.

The raw materials such as Portland clinker, gypsum for CEM-I type cements and trass

(pozzolan), limestone, slag, fly ash are for CEM-II type cements, which are fed to the bunkers

(1) continuously. The raw materials shall be dozed as per required flow using the weighing belt scales (2) placed under the feeding bunkers (1).

The function of the weighing belt scales (2) is dosing of any raw material and re-adjustment as per the actual raw material flows automatically. Raw materials are transferred to the first ball mill from the weighing belts (2) through the feeding conveyor (3). Quantities of raw materials are measured by the speed controlled weighing belt scales (2). Quantities of raw materials on the weighing belts (2) are weighted continuously online and in consideration of the monitored speed of weighing belts, the actual material flow is calculated instantaneously. The actual material flow and the programmed flow are compared by PID Controller to calculate for adjustment of speeds of the weighing belt scales (2) for re adjustment of such speeds instantaneously.

In consideration, the comparison of the actual flow and the programmed flow the speed is increased or decreased accordingly. The quantities of raw materials are calculated using the weighing measurements on the load cells of the weighing belt scales (2). The speeds of the weighing belts are calculated by considering rotation speeds of wheel drums.

All measurements and adjustments can be made on the control panel placed on the MCC Panel which can be controlled by programmable computer system. Furthermore, any instantaneous measurements can be observed continuously.

Besides monitoring the actual instantaneous flow measurements, cumulative quantity of raw materials passing over the weighing belt scales (2) can also be monitored. To communicate with the other equipment the programmed and actual flow values are measured in 4-20 mA scale. Continuously increasing pulse relay indicates every ton of measure by dry contact information.

The weightings are performed as per the recipes with automation system. The recipe contains; recipes name, lot number, percentage of programmed quantity and quantity in total, for modifier, clinker, gypsum, fly ash etc. The percentage inputs in recipes for each material like clinker, gypsum, limestone, slag, fly ash are multiplied by the quantity of end product to be produced and hourly feeding rate of each component to the first ball mill (6) are calculated by the system automatically.

The quantity of modifier to be fed into the first ball mill (6) is adjusted with respect to the programmed percentage of clinker by weight. As the content of clinker in cement changes the percentage of modifier also changes accordingly. The modifier is fed to the second ball mill (12) in relation to actual recorded clinker quantity fed into the first ball mill (6) from the modifier silo (8) by the modifier feeding system (9). As a result, while fine grinding the modifier will be ground together with the other materials to enable the dispersion of the modifier to the whole mix.

Various Cement types with different properties can be produced using the recipes depending on High Performance cement classes and qualities.

Sample 1 : Portland Cement

Product Type: CEM I

Total Recipe Kg: 50,000 kg/hr

If modifier is programmed to be %1 of the clinker;

Clinker to be % 95; so clinker in flow = (95/100)*50.000 kg/hr= 47,500 kg/hr

Gypsum to be % 5; so gypsum flow = (5/100)*50.000 kg/hr = 2,500 kg/hr

The quantity of the modifier shall be %1 of clinker; and flow = (1 /100)^*47,500 kg/hr = 475 kg/hr.

Sample 2: Portland Pozzolan Cement

Product Type: CEM Il

Total Recipe Kg: 50,000 kg/hr

If modifier is programmed to be % 0.5 of the clinker;

Clinker to be % 75; so clinker flow = (75/100)^*50,000 kg/hr= 37,500 kg/hr

Gypsum to be % 5; so gypsum flow = (5/100)*50,000 kg/hr = 2,500 kg/hr

Trass to be % 20; so trass flow = (20/100)*50, 000 kg/hr = 10,000 kg/hr

The quantity of the modifier shall be %0.5 of clinker; and flow = (0.5 /100)*37,500 kg/hr = 375 kg/hr.

Different recipes can be prepared with different ratios and quantities considering various raw materials for each product. Once the production started as per the programmed recipes, the raw materials are being weighed with the specified ratios by the weighing belt scales(2) and transferred to the first ball mill (6) by the first mill feeding conveyor (3). The Dedusting is performed by the Filter (4) placed over the feeding conveyor (3). The balls located in the first ball mill (6) are 90 mm-60 mm that can perform coarse grinding approximately at the range of 0-

500 mm micron.

As a result of adjustable air flow of the filter (5) placed over the first ball mill (6), the ground material with the required fineness shall be transferred to the air slide (7) connected to the elevator feeding (10) the second ball mill (12).

The modifier is simultaneously fed to the second ball mill (12) from the modifier silo (8) by the modifier feeding system (9). Fine grinding of the mix for finished product shall be perform in the second ball mill having various size balls from 60 mm to 15 mm.

The ground material passes through the separator (16) where the particles with the specified fineness defined at any range from 3500 to 9500 blaine are separated and transfers to the product silos (20-21), while any coarser particles are transferred back to the second ball mill

(12) for further grinding. The filters (5, 14) adjust the flow and speed of the material flowing through the first ball mill (6) and the second ball mill (12) while performing dedusting as well.

The feeding system (9) and the conveyor belt (11) are replaced under the modifier silo (8) in order to control rate of feeding of the modifier to the mix.

The cement particles separated to the required fineness (blaine) by the air swept and adjustable separator (16) is transferred to product silos (20, 21) by the transfer units (19) placed over the silos (20, 21). The coarse particles above the required fineness are conveyed back to the second ball mill (12) through air slides (13) for regrinding.

The High Performance Cement stored in the silos (20, 21) is delivered to the customers either as bulk by cement trailers (29) or in packages by the trucks (28). The packing unit consists of an elevator (22), filter (23), screen (24), bunker (25), bag filling station (26) and screw (27).

Although, in order to produce High Performance Cement a single mill with two compartments can also be used as an alternative to two mill (6,12) setup, it is not as effective as two mills each acting as a separate compartment where modifier is fed in to the second compartment before fine grinding. High Performance Cement can also be produced by feeding modifier while regrinding of the already produced cement.

The scope of the Invention covers to produce cements in other strength classes like; 32.5, 42.5,

52.5. The impact of the High Performance Cement Plant to the environment is not different than normal cement plants. There shall be no adverse effect by the Invention to the chemical composition of the cement either.

The dedusting during the production of High Performance Cement shall be achieved by using various filters (4, 5, 14, 18, 23). All production process is in closed cycle where dust and solid particles emission is below the allowable limits that can be verified by any air quality control testing.

Like any other cement type, High Performance Cements are also compatible with other construction materials and can be used for similar applications as other cements. High Performance Cement can be utilized in high rise buildings, airport runways, bridges, marine and land works with special applications, sea structures and prefabricated concrete elements, where high strength and/or high performance is required.

On the other hand High Performance Cement has the property of non-shrinking for excellent use for joint fillers, grouting. The mortars produced by using HPC are resistant to permeability, high temperature differences and frost-defrost. Therefore, HPC can be used for such requirements, as well as precast concreting to avoid steam cure for early removal of the formwork, which provides advantages that can not be ignored.

Using High Performance Cement provides workability, early and high strength, impermeability for concrete which results no need for other additives. Therefore, eliminating any other additive during concrete production will prevent possible dosing problems but anti freezing additive may be needed against frost during winter period.

High Performance Cement should be utilized without using any other additives during concrete and mortar production, where water cement ratio should not exceed 45 %. When water/cement ratio is kept at the range of 40-45 % in concrete mix designs, slump value shall be 80-120 mm and high strength shall be achieved. The water demand of the High Performance Cement is less, so while mortar testing consistency of mix should be considered instead of 0.5 w/c ratio as defined in related Cement Standards

The results of various concrete tests performed shows that compressive strength of 1000 kg/cm² can be achieved easily by using normal aggregates. Furthermore, it is also found that; the most convenient water cement ratio is 44 %, while the slump test results for dispersion was

185-190 mm. The results of such tests are given in the below tables.

Table 2. below shows the composition of the HPC 62.5 in weight ratio. Content Weight Ratio (%)

Clinker (C₃S >60) % 94-95

Gypsum % 5-6

Modifier % 1-1,5 (of clinker)

Cement Mortar Strength

The Table 3 below shows the comparison of compressive strength values for both Normal Portland Cement and High Performance Cement. Table 3. Compressive Strengths of the Cements (kg/cm²). Cement Type 2days 7days 28days

HPC 62.5 325 558 730

PC 42.5 220 346 470

SC 32.5 105 210 357

* HPC 62.5R shall mean with special concrete additive.

The protection area of this application has been specified under claims and cannot be limited to the descriptions only given as sampling above. It is clear that any innovation can be provided by a person skilled in the related art by use of the similar embodiments and/or can also apply this embodiment in other areas for similar purposes used in the related art. Therefore, it is also clear that such embodiments lack of novelty criteria.

Claims

1. A production process of High Performance Cement (HPC) to be used in the construction sector, and it consists of process steps which are;

- placing of the all raw materials, which shall be Portland clinker, gypsum and additives for composite cement production such as limestone, slag, sand, trass (pozzolan) etc., into the feeding bunkers (1) for production of High Performance Cement depending on defined cement quality and classes,

- automatic dozing of raw materials as per required using belt scales (2) placed under the feeding bunkers (1),

- measuring of the raw materials on the weighing belt scales (2), comparing the actual flow and the programmed flow by monitoring the speed of the weighing belt scales (2) and readjusting the speed of the weighing belt scales (2) accordingly,

- dedusting of the raw materials by placing filter (4) above the weighing belt scales (2),

- transfer of the raw materials to the feeding conveyor of the first mill (3),

- feeding of the raw materials from the conveyor (3) to the first ball mill (6) for coarse grinding less than 500 microns,

- suction of the semi-ground material in the mill (6) by the filter (5) above the mill (6) and transfer to the elevator (10) through the air slides (7),

- feeding of the coarse ground material to the second ball mill (12) by the elevator (10) and also feeding of the modifier with a determined ratio to clinker quantity from the modifier silo (8), and fine grinding at any range from 3,500 to 9,500 blaine as per the type of the end product,

- suction of the finished product named as High Performance Cement by filter (14) at the exit of the second ball mill (12) and transferring to the elevator (15) by air slide (13),

- transferring of High Performance Cement to the air swept separator (16) from the elevator (15),

- the separation of fine cement to the required particle size in the separator (16) and transferring to the elevator (17) by the air slide (13), and

- transferring the cement to the silos (20,21) from the elevator (17) by the cement transfer units (19).

2. Process according to Claim 1 , characterized in that one of the process step is the returning the cement particles, which are separated by the separator (16) and not ground to the required fineness, back to the second ball mill (12) through the air slides (13) for re-grinding.

3. Process according to claim 1 , characterized in that one of the process step is the placing of high performance cement in the silos (20,21) for delivering to the customers either by Bulk Cement Trailers (29) or in bags at bag filling station (26).

4. Process according to claim 1 , characterized in that one of the process step is the feeding of the modifier from the modifier silo (8) to the second ball mill (12) by modifier feeding unit (9), in the ratio of the raw material passing through the raw material conveyor (3) band of first mill.

5. Process according to the preceding claims, characterized in that it is achieving water cement ratio of the concrete and mortars to be 40-45 % by using the high performance cement (HPC) without using any other concrete additives.

6. High performance cement, which are produced by the process according to claims 1-5, having Portland clinker and modifier with a certain ratio as per the quantity of clinker used and type of cement produced, and gypsum, slag, limestone, sand, fly ash, trass (pozzolan); or cement of known strength classes using reduced clinker content.