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CUCC Qingzhou Cement Co.,Ltd. 6000t/d Cement Production Line

1. Basic Information

CUCC Qingzhou Cement Co., Ltd. is individual proprietorship invested and built by China National Building Materials Group (CNBM) and China United Cement Corporation (CUCC), and the original name was CUCC Qingzhou Luhong Cement Co., Ltd. The preliminary work of the project experienced long tortuous process, even after the official approval documents issued by former State Planning Commissioning according to views of Prime Minister's office in May, 2001, the project had been unable for timely construction. CNBM and CUCC, based on its own development strategy, after several visits and repeated consultation and negotiation with people’s government of Qingzhou, reached a cooperation agreement of “overall planning, implement with step by step, make preparations for the construction of a 6000t / d clinker cement production line at earlier date”. Meanwhile CUCC entrusted Nanjing Kisen International Engineering Co., Ltd. as main designer for the project as per demand of construction procedure for cement project of CUCC, and further carried on preparation work and added the implementation of construction condition; In addition required to complete related work procedure regarding change of project investment entity. On April 16th, 2004, National Development and Reform Commission (NDRC) issued document of “reply letter from NDRC regarding change on owner of Foreign-owned Shandong Qingzhou Cement Co., Ltd.” under letter No. of industrial [2004]621. On November 17th, 2004, NDRC again issued “reply letter regarding change on Construction scale of CUCC Qingzhou Luhong Cement Co., Ltd.”

The project construction was started in April, 2004 with foundation construction the first to be started, but the project construction was in status of half stopped or shutdown in September in the same year due to shortage of construction funding; The project civil construction was not fully restored until end of 2005(previously the foundation work had been basically completed), and into igniting commissioning phase in Dec. 2006 and put into operation in Feb. 2007 then pass through performance test in April, 2007 thereafter smoothly put into commercial operation.

Under the effective management of CUCC Qingzhou the actual operating conditions after put into operation exceeded the design assessment requirements. For this reason the project was awarded the first prize of 14th excellent engineering design achievement reward of building material industry issued by China Building Materials Construction Society in 2009.

2. Main technical difficulties and outstanding features

1)The first technical difficulty of this project is targeted application of limestone with high-magnesium, high alkali chloride, poor burnability and grindability. Initially one of a major reason for change of project investment entity is because that the quality issue of limestone is hard to be finally concluded and eventually give up. Nanjing Kisen, based on in-depth study on resources exploration and harmful ingredients, researched and adopted comprehensive technology with independent intellectual property rights of double series five-stage cyclone preheater + online double spouting calciner + high speed type rotary kiln + high efficiency grate cooler + specially designed coal burner, and without bypass system, satisfactorily resolved problems of poor burnability, crusting and clogging of limestone, and it was also the first 6000t/d production line undertaken by Nanjing Kisen at that time.

2)Because the 6000t/d capacity was the first domestic-made production lines at that time, combined with the special influence of limestone materials, therefore the second technical difficulty of this project lies in aiming at the limestone materials with poor grindability, how to achieve reasonable matching between selection & amplification of raw mill and the resulting preheater exhaust gas treatment system, and also needs to take into account the reliability issue after large-scaling of domestic made equipment. For this purpose Nanjing Kisen had a unique technical insight into system configuration with significant achievements. In addition, the antecedent of the second technical difficulty was because the limestone mining followed design principle of non-exhaust emission.

3)Because the construction site is collapsible soil formed by low-lying topography deep backfill, and collapsible level of sub-regional is different, leading to foundation treatment as the third technical difficulty for this project. Nanjing Kisen properly classified general layout pattern of each production area as per collapse features of each area of construction site, and comprehensively considered demand of construction of WHR system as supporting of production line and reserved planning for expansion line etc.; stressed the emphasis on design scheme of optimizing different piling and foundation as per regions on condition ensuring engineering safety, reliability and economic efficiency, and meanwhile gave overall consideration on intersectionality between civil cost and engineering safety. 

3. Main production operation status

After the project was completed and put into operation in Feb. 2007, the annual average clinker output of kiln system has been maintained at 6350 ~ 6500t/d, with maximum capacity once reached ~ 7000t / d, preheater C1 outlet air temperature 290~305 ℃, outlet negative pressure 4960~5100Pa, the pass rate of f-CaO ≤1.5% in clinker not less than 85%.

According to production statistics: When adopt 20~30% outsourcing high quality limestone in collocation as supplement raw materials, the production condition of kiln system would be better with standard coal consumption could reach 102~104kg / t-cl; but generally only the limestone of plant-owned mining is used for normal production, under which situation the standard coal consumption could reach 107~108kg / t-cl; analogy unit clinker power consumption is ~58kWh/t-cl (14kWh/t-cl shall be increased additionally because of the supernormal part of grindability of limestone ); clinker 28d strength of 53~56MPa. But because this production line is running stably and reliably with analogy various technical indicator are preferable in CUCC cement benchmarking management so far, therefore leadership of all levels from CNBM and CUCC have repeatedly paid visit to site and gave fair evaluation to this production line.

Another issue need to be mentioned is that because the poor grindability of limestone material and the roller type raw mill supplier selected by owner was the first time to design and manufacture the large-scale equipment at that time, therefore the actual output of the mill system is low but with relatively high installed power configuration resulting in high power consumption of raw material preparation system; Meanwhile raw meal fineness of mill outlet is hard to be effectively controlled, and 0.2mm residue is often out of limits, which made the current clinker heat consumption, power consumption, strength, etc. not fully meet the scheduled design value. In addition, there are still some defects on quality of this roller type raw mill, especially the key components such as roller bearing and hydraulic system have repeatedly caused major quality accidents leading to shutdown of whole production line. These factors also limit the maximum exertion of clinker burning system capacity.