Duties and activities of the cement laboratory:

- Chemical analysis of raw materials for determination of percentage of oxides

- Projection of the raw material mixture according to the results of chemical analysis, taking into account the type and quality of cement produced and the cost of delivery and production, including drying, wear resistance and hardening ability of materials.

- Pre-mixing, homogenization of the charge with the goal of reducing chemical oscillations and reducing the inhomogeneity of the charge fed to the furnace.

- technological control, including the control of the humidity of the raw materials, chemical composition, as well as the softness and roughness of the charge, free lime and mass per liter of clinker, the percentage of firing and the amount of volatile components of hot materials when entering the furnace, the ratio of mixing clinker and gypsum and softness or cement roughness

- Chemical analysis and physical testing of cement to ensure quality compliance with desired technical specifications, national and international standards.

- Issuance of a permit for the transportation of cement for consumption

- Measurement of concrete settlement and clamping strength according to the standard

- Distribution of grades of sand according to the standard

- Concrete production with other mixing plans to better respond to the needs of consumers

1_4 Chemical laboratory

Clay and limestone minerals usually include oxides of CaO, SiO2, Al2O3, Fe2O3, MgO, SO3, K2o, Cl, Na2O, L.O.I. to be These measurements are usually done by two methods, instrumental analysis and non-instrumental analysis. As an example, the measurement of alkalis, including K2O, Na2O, is done by a flame photometer. In non-device analysis, weight and volume methods are used in measurements.

2-4 Material regulation laboratory with X-Ray device

     One of the most important parts of the laboratory is the material regulation part because the performance of this part has a direct effect on the kiln performance and ultimately the quality of clinker and cement produced.

The cement kiln is a chemical reactor in which the main oxides present in the kiln feed in liquid phase react together and create the crystal phases that make cement. The ratio of each of the oxides to be combined or the ratio of the raw materials to be mixed based on the defined modules of the cement industry is determined by the materials regulation department. These modules are defined as follows:

1-2-4 L.S.F (lime saturation factor)

According to the klin temperature, CaO usually combines with them, without melting, in the liquid phase resulting from the ternary system of Al2O3, Fe2O3 and SiO2, and forms the main components of cement.

Preform phase 2CaO+SiO2                                                 2CaO.SiO2 (C2S)

Alite phase C2S+SiO2                                                        3CaO.SiO2 (C3S)

Aluminate phase 3CaO+Al2O3                                          3CaO.Al2O3 (C3A)

Aluminum ferrite phase 4CaO+Al2O3+Fe2O3                 4CaO.Al2O3.Fe2O3 (C4AF)

In the above reactions, CaO as one of the main components of the reaction combines with other oxides and creates the desired phases. Theoretically, CaO should combine with 2.8 times SiO2, 1.18 times Al2O3 and 0.65 times Fe2O3, which is called CaOmax. which means: CaOmax = 2.8SiO2+1.18Al2O3+0.65Fe2O3 On the other hand, there is always some CaO present in minerals, so the ratio of CaO in minerals to CaOmax has been called lime saturation factor (LSF).

 

 The optimal amount of raw material for firing in Neka cement is 92-90. The higher the LSF, the more difficult it is to burn and the more thermal energy required to burn the clinker.

2-2-4 SM (silicon module)

shows the ratio of the solid phase to the liquid phase and its optimal value for the furnace charge is 55, 35-2 , 2.

    SM = SiO2/(Al2O3+Fe2O3)

 

3-2-4 AM (aluminum module)

shows the ratio of oxides forming the liquid phase and its optimal value for

kiln feed 60.30-1,1.

 AM = Al2O3/Fe2O3

 

4-2-4  l.f. (liquid phase):

It shows the percentage of liquid phase in the klin and its optimal value is in the range of 24-26%.

L.Ph=2.95*Al2O3+2.25*Fe2O3+MgO+K2O+Na2O

The tests carried out in the materials control laboratory are as follows:

4-2-5 Carbonate test (titer):

     This test is performed to determine the total amount of carbonates in raw materials, kiln feeds, and materials entering the mixing department. Thus, 20 ml of normal hydrochloric acid is added to one gram of sample and the reaction between carbonates and hydrochloric acid is carried out in the presence of heat, after about 5 minutes the cold solution is titrated in the presence of phenolphthalein reagent. In other words, the titer is calculated from the following ratio.

  5 * (2/ volume of soda consumed - volume of acid) = titer (percentage of carbonates)

4-2-6 Testing of materials entering the mixing halls:

     A 500 grams sample is taken every hour from the materials entering the mixing hall number one by the automatic sampler. The mentioned sample is transferred to the laboratory by the operator of the hall, and the titration test and chemical analysis are performed on it with the X-Ray machine, and the required changes are communicated to the crusher unit for the type of raw materials used.

In order to regulate the materials of mixing hall number 2, an online analyzer device (Online Analyzer) has been installed at the entrance of the mixing hall, which sends chemical analysis to the laboratory every minute of the materials entering the hall, and based on these results, the pile adjustment by The laboratory takes place.

4-2-7 Output materials from material mills:

     Every hour, one sample is taken from the materials coming out of the material mills by the automatic sampler and sent to the laboratory by the sample sending system. Titration test and chemical analysis are performed on these samples by X-Ray machine. After the test, the results of the titer percentage and LSF, SM, AM modules are reported to the control room, and if necessary, the necessary changes to correct the materials are announced to the control room, and the control room is obliged to notify the tonnage of each of the materials entering the material mill to X-Ray operator.

4-2-8 incoming materials into the kiln:

To know the condition of the materials entering the kilns to help the kiln operator adjust the fuel and produce clinker of the desired quality, samples of the materials entering the kilns are taken every 2 hours and titration and chemical tests are carried out. An X-ray analysis is carried out on them, which is done and the result is reported to the control room.

4-2-9 -Other materials:

In addition to the above, the following studies are carried out in the X-ray laboratory:

A: Clinker chemical analysis test

      At the end of the day (after 24 hours), the clinkers produced are collected, ground into powder and analyzed using an X-ray machine. To ensure proper operation of the X-ray machine, this test is also performed in a chemistry laboratory.

B: Analysis of loading cement and cement mill

The cement produced by the cement plant is analyzed in the X-ray laboratory to ensure proper quality and SO3 percentage and, if necessary, necessary changes in the gypsum-clinker mixing ratio are transmitted to the control room.

Also, the cement supplied to the customer is subjected to chemical analysis daily in the X-ray laboratory and chemical laboratory.

3-4 Physics Laboratory:

In the physics laboratory, the physical properties of raw materials, clinker and cement production are monitored during the production process. The experiments carried out in the physics laboratory are as follows:

1-3-4 Test to determine the softness (or roughness) of raw materials and kiln feed

The roughness of the samples that were brought to the laboratory by the X-Ray sampler for titration and chemical analysis was determined in the physics laboratory by the Alpine sieve (sieve equipped with a suction system) on the 4900 mesh sieve (diameter 88 microns) and the 900 mesh sieve (210 microns) and it is reported to the control room. This test is done once every hour for materials coming out of material mills and once every 4 hours for kiln feed.

2-3-4 Testing the clinker liter weight

The liter weight is the weight of a quantity of clinker that occupies the volume of one liter, and it is also called density in scientific terms. In this test, particles of clinker that pass through a 12 mm sieve and remain on a 6 mm sieve are tested. In this test, a sample is taken every hour by a physical sampler from the outlet of the cooler, and after sieving, it is poured into a special container whose volume is one liter, and after weighing, the result is reported to the control room.

The liter weight is an important indicator of the quality of cooking ingredients in the klin . So, if the mass of a liter of clinker is high, then this indicates that the clinker pellets are more dense and the molten state of the material is greater, and if the mass of a liter is less, then this indicates that the clinker pellets have a lower density and clinker compounds with a large intermolecular space have a higher density. Determining the liter weight of clinker is a simple method that shows the quality of the firing conditions in the kiln. The  liter weight of clinker is 1250-1150 grams per liter and if it is too high or low, the quality of the clinker will not be good. It should be noted that if the liter weight of clinker is less than 1000, then the clinker is of poor quality and the kiln operator must send the clinker produced in the kiln to the sub route as a non-conforming product to make decision.

3-3-4 free lime of clinker and cement

Since calcium oxide (CaO) plays an important role in cement production and is the main constituent of Portland cement, it can also cause the quality of the cement to deteriorate or become unusable and unfit for use and meet the standard.

One of the important points is the presence of free CaO in clinker and cement. Free CaO or so-called free lime should not exceed 2.5%, since free lime causes swelling and rupture of concrete during hydration. When combined with other oxides, cement or clinker, the amount of free CaO in clinker is greater and is minimized.

In this test, once every three hours, a free lime test is carried out from clinkers collected simultaneously with the collection of a liter sample of all fractions and the result is reported to the control room.

Also, the free lime test is done once in each shift from the output cement of the cement mills.

4-3-4 Initial and final adhesion of cement

     After the production of clinker, in the production process in the cement mill, in order to control the adhesion of cement (preventing premature adhesion), about 7-5% hydrated gypsum (CaSO3, 2H2O) is also milled along with the clinker. The adhesion time of cement is one of the main factors in the physical quality of cement. In this test, the cement sample is mixed with an appropriate amount of water and poured into a special rubber mold, and the required percentage of water, the initial adhesion and the final adhesion of the produced cements are determined by the Vicat machine with special needles.

5-3-4 Determining the blaine of cement

     In this test, the blaine of the cement sample is determined. That is, what is the blaine of one gram of cement sample, so its unit is Cm2/gr.

Obviously, the softer the cement, the smaller the space between the grains and the higher the blaine of the cement. The test is based on the fact that when the air passes through the cement sample that was placed in the special cell, the liquid that was brought up in the U-shaped tube before, goes down again with the pressure of the air passing through the cement tube.

The time required for the passage of air to a certain amount (or for the liquid to drop in the tube to a certain amount) is measured and the blaine of the sample is determined. This test is done every two hours for the cement mill and the result is reported to the operator of the control room. Due to the fact that this test is measured by the blaine device, the special level of cement is also called blaine of cement. Also, due to the fact that the blaine of cement is defined as at least 2800 cm2/gr according to the national standard of Iran, the amount of cement in a cement mill should not be less than the above number.

6-3-4 Cement roughness test

In this test, the remaining amount of cement on a 4900 mesh sieve is determined by Alec Alpine and reported to the control room operator every two hours.

The important point in this test is that there is a proportionality between the blaine of cement and the roughness on the sieve 4900, if the blaine is high means that amount of cement on the sieve will be less.

7-3-4 Strength testing of cement using the Press method:

In this test, a mortar with a ratio of 450 grams of cement, 1350 grams of standard sand and 225 cc of distilled water was prepared from the daily delivery cement sample and the prepared mortar was poured into 16x4x4 cm molds and after vibrating for 24 hours in a box at room temperature It is kept at 19-21 degrees Celsius and the humidity is above 90%. After 24 hours, the above samples are kept under water from the open mold as samples for 3, 7 and 28 days, and are tested for bending and compressive strength on the desired date. The compressive strength factor is one of the most important factors that determines the conformity of cement with the standard.

8-3-4 Cement expansion test

     As mentioned earlier, free CaO is the cause of swelling of cement during the hydration stage, in addition to free CaO, high percentage of MGO, SO3 causes swelling and increase in volume of cement. This increase in volume is measured in the physical laboratory for the supplied cement using an autoclave device. Thus, by adding a certain amount of water to 500 grams of cement (this amount is determined by the adhesion test), a cement paste of conventional concentration is prepared and 350 grams are poured into a mold measuring 285*25*25 mm, which has indicator needles and vibrate with a vibrator. It is possible to place the mold in a box with a humidity above 90% for 24 hours and after 24 hours the mold is opened and its initial length is measured and the mold is autoclaved for 2 hours at a temperature of 350 degrees Celsius and a pressure of 20 bar. It is also placed after cooling measure the length and report the difference in length as the percentage of expansion. According to the standard, this number should not be more than 0.7%. This test is an indication of the health of the production cement and is an important factor in terms of standards.

4-4 Concrete laboratory

Mazandaran Cement Company, fully believing in the importance and position of customer satisfaction as its highest priority, has established a specific laboratory.

This laboratory has been established to provide information and advice to cement consuming companies, including concrete companies, construction projects and other companies that are active in the field of concrete production and consumption, and all physical testing of concrete is carried out in accordance with ISIRI and ASTM standards. .

In this laboratory, in order to satisfy customers and compare the behavior and resistance of manufactured cement concrete with materials available on the market (fine and coarse aggregate), as well as to improve monitoring and ultimately improve product quality, the following tests are carried out:

 

- Sampling of fresh concrete in accordance with ISIRI3201-1 and ASTM C172 standards

- Concrete flow test in accordance with ISIRI3203-2 and ASTM C143 standards

- Compressive strength testing of concrete in accordance with ISIRI 3206 and ISIRI 6048 and ASTM C39 standards.

- Aggregate granulation test according to ISIRI4977 and ASTM C136 standards.

- Production and testing of concrete samples in ISIRI581 and ASTM C31 laboratories