2023, the mandatory national standard GB 175-2023 "General Portland Cement" formulated by the Ministry of Industry and Information Technology was approved and issued by the State Administration of Market Supervision and Administration and the National Standardization Management Committee, and will be implemented on June 1, 2024. At present, there are several articles on the interpretation of the new standards, most of which are based on the interpretation of the provisions of the standards. Here we do not judge the new standards, but only analyze and summarize from the perspective that cement enterprises should strictly implement the standards. As a cement production enterprise, how to take what action measures to maximize the interests of enterprises under the premise of compliance.
1. Measures
to deal with the new requirements for components The new standard stipulates that the mixed materials include granulated blast furnace slag/slag powder, fly ash, pozzolanic mixed materials (5 kinds of natural pozzolanic mixed materials and 5 kinds of artificial pozzolanic mixed materials), limestone and sandstone, totaling 14 kinds. The specific applicable standards of these materials are given: GB/T 203 Granulated blast furnace slag for cement, GB/T 2847 Pozzolanic admixture for cement, GB/T 5483 Natural gypsum, GB/T 1596 Fly ash for cement and concrete, GB/T 21371 is used for industrial by-product gypsum in cement, GB/T 35164-2017 is used for limestone powder in cement, mortar and concrete, only sandstone and limestone have no reference standard number, and the component measurement is carried out according to GB/T 12960 standard. For cement enterprises, the following measures should be taken:
1.1. Check whether all the admixture resources currently used are within the scope of the new standard list, and survey the admixture resources in the new standard list around the enterprise.
At present, some cement enterprises still use steel slag, manganese slag, lithium slag and other admixtures that do not meet the standards and specifications. After the implementation of the new standards, they can no longer be used. How to replace raw materials requires the director of the laboratory to cooperate with the supply department to conduct a detailed survey of the raw materials around the enterprise that meet the new standards. The laboratory shall issue the internal control quality requirements for the new admixture and conduct sampling, analysis and judgment, and the Material Supply Department shall be responsible for the commercial accounting of the price to the factory. Then the laboratory designs a new cement proportioning scheme according to the new standard, carries out small grinding experiment verification, combines with the price of various mixed materials provided by the supply department, and gives the latest proportioning scheme design of various varieties and grades to the company's leading group for decision-making. 1.2
The sales department shall combine with the laboratory to give suggestions on whether the current cement variety and grade of the enterprise need to be replaced after the new standard is issued. In
some areas where admixture resources are scarce, combined with the situation of admixture resources and local cement demand, market usage habits, competitors'varieties and grades, and the number of cement product warehouses in enterprises, whether the cement varieties produced by enterprises need to be changed after the implementation of the new standards, and if so, what specifications of cement varieties and grades will be changed. Analyze the cost and market situation, and make a detailed feasibility report for the company's leaders to make decisions. If a new cement variety is produced, the laboratory should follow the new product development process, which takes a long time and needs to be done quickly.
At present, from the point of view of the lowest cost, many small grinding stations have the lowest cost to produce M32.5 grade cement, and some areas with abundant admixture resources have the lowest cost to produce limestone Portland cement, steel slag Portland cement, magnesium slag Portland cement and other varieties of cement, but they should be combined with the actual situation of the local market. Whether the new product cement can be accepted by the market or not, we should make a prudent choice. Before and after the decision is
made, the laboratory has to carry out a large number of small grinding experiments and large grinding experiments, make products for inspection and certification, change the production license, etc. The production department also has to adjust the mill gradation and operation for new admixtures or cement varieties, which affects the whole plant.
In any case, we must remember to use or clean up the materials that do not conform to the new specifications in the enterprise before June 1, 2024, so that they can not be retained on the spot, leaving no future trouble.
2. Adjust
the fineness index required by the new national standard accordingly. The new national standard stipulates that "the fineness of ordinary Portland cement, slag Portland cement, fly ash Portland cement, pozzolana Portland cement and composite Portland cement should not be less than 5% expressed by the screen residue of 45 μm square sieve". At present, in order to reduce the cost, quite a number of cement enterprises add less clinker , the fineness is too fine, the screen residue of 45μm square sieve is less than 5%, which does not meet the new standard, and the energy consumption, cost and the production situation of the mill after changing the ratio need to be considered comprehensively. For the operation or process adjustment of the mill and powder concentrator, if only the operation and process adjustment can not meet the requirements, the hardware transformation must be carried out. Each enterprise should carry out comprehensive transformation according to the actual situation of its own enterprise, balance the fineness, machine-hour, power consumption, cement performance, intellectualization and other factors, regardless of its own transformation. Or invite professional technical transformation companies and design institutes to carry out transformation, the transformation cycle is longer, the transformation cost is higher, the time is very urgent, the production department needs to make decisions as soon as possible, and carry out scheme demonstration in advance.
3. In view of the new national standards for cement enterprises
producing slag Portland cement, fly ash Portland cement, pozzolana Portland cement, composite Portland cement and slag Portland cement at present, the three-day strength of these varieties has been improved, which is the same as that of P.O grade cement. In addition, the requirement for fineness should not be too fine, which requires enterprises to increase the amount of clinker added in batching to achieve three-day strength to meet the standard requirements. According to their actual situation, enterprises formulate new internal control standards, and through small and large grinding experiments, explore a production formula that not only meets the requirements of the new standard, but also achieves a good balance in economy. After the implementation of the
new standard, components, as a necessary testing item, require enterprises to test themselves first and purchase professional testing instruments, such as carbon dioxide analyzers. Cement component determinator, fly ash ammonium ion determinator, water-soluble chromium (VI) determinator and other professional instruments and relevant standard samples, carry out relevant learning and training (including training on the determination method of methylene blue value in limestone), instrument calibration and other work, and analyze the difference between the actual detected cement component ratio and the real cement component ratio.
At the same time, according to the qualified requirements of autoclave stability required by type inspection, it is suggested that enterprises with magnesium oxide content exceeding 4% in clinker purchase autoclave and do autoclave stability test by themselves. If it is a group enterprise, several enterprises can jointly purchase one autoclave or the central laboratory of the group can purchase one autoclave and entrust it to carry out the inspection. After all, the cost of third-party autoclaving stability testing is not low, and the testing time is long. Radioactive detection equipment is relatively expensive, and it is generally sent for inspection.
5. Suggestions
on the purchase of cement particle size analyzer The cement screen residue curve has a great impact on the quality of cement, the adaptability of additives, the strength of clinker, power consumption and cost, and can also better guide the cement grinding process and operation adjustment, which is very important for the production of cement enterprises. It is suggested that qualified enterprises directly purchase online cement laser particle size analyzer in one step, which is also convenient for enterprises to carry out overall intelligent transformation, or purchase offline laser particle size analyzer for laboratory with relatively cheaper price to regularly detect the distribution of cement particles and better guide production.
6. Participate in training and meetings in many ways to understand the standards and adapt to the standards
. At present, many authoritative organizations are interpreting the new standards. Cement associations, quality inspection institutes, cement quality inspection stations and other organizations are also organizing experts to interpret the new standards for training. Participate in training and meetings in this area to understand the standards in many ways; Some large enterprise groups can invite authoritative experts to hold internal discussion and analysis meetings, for example, to determine the uniform format of factory certification materials, 3-day factory inspection reports and other types of report formats within the group; the group unifies the scheduling of regional admixture procurement and production bases and other resources, different production bases produce different types and grades of cement, and conduct differentiated market competition. How to deal with the problem that the cement produced by different varieties of the
same mill does not meet the standard? In some cases, the strength of cement does not meet the requirements, and there is no clear solution to the problem of lowering the grade and not meeting the requirements of new components, so we need to concentrate our wisdom to solve it.
Summary: The implementation time of the new standard is very short. The standard has been released. No matter how many opinions and suggestions there are, there is no way to change the standard. As an enterprise, it can only passively, comprehensively and accurately understand the content of the standard. According to the actual situation of the enterprise itself, it can seek advantages and avoid disadvantages, turn inward and practice hard. Continuously reduce their production costs, improve the quality and performance of cement, win a good reputation in the market, win the peers in the current industry trend, and make their enterprises develop better.
