目前,我国大部分有铜存货的上市公司都已经参与到了期货市场中,通过铜期货交易以对冲公司所面临的财务风险,稳定生产经营.然而,由于宏观市场环境和行业环境存在的外部风险和企业本身所存在的内部风险,一些企业在运用铜期货进行套期保值时可能并没有很好的对冲企业所面临的财务风险,反而会造成一定的损失.本文以江西铜业为例,通过建立财务风险指标以监测企业财务状况,通过简单回归分析判断公司套期保值的效果对企业财务能力的影响,并针对结论作出分析与评价.

Ultrafine ground calcium carbonate (GCC) produced by carbonate minerals is a widely used inorganic powder material. In order to get a finer GCC powder with narrow distribution span, effects of rotation speed and media density on particle size distribution and structure of GCC were studied. The grinding limit-particle size and distribution of GCC were measured by centrifugal sedimentation granulometer. The specific surface area, average particle size and structure of ground GCC were characterized by X-ray diffraction (XRD) and BET. The morphology of particles was observed by a scanning electron microscope (SEM). The result shows that low rotation speed and high-density media are conducive to obtaining a smaller particle with narrower size distribution. The crystal plane (012) and (122) of GCC are more stable than (018) and (202). (C) 2014 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

为了研究CJXXM型行星磨干法超细研磨皂石的效果,采用单因素法进行实验,通过粒度分析考察介质与物料质量比、磨机转速、助磨剂种类及用量、磨矿时间对皂石粒度的影响.结果表明,选用粒径为0.6～2 mm的钇稳定氧化锆球作为研磨介质时,优化工艺条件是介质与物料质量比为3,磨机转速为600 r/min,添加质量分数为0.6％的硬脂酸钠为助磨剂,磨矿时间为30 min;在适宜的工艺条件下,产品的d50、d97分别为1.55、7.38 μm.

This work investigated the size reduction process of calcined black talc using a high energy CJXXM planetary mill. The grinding effects of two different grinding media, aluminia and zirconia, and three kinds of grinding aids, ethanol triethanolamine and sodium hexametaphosphate on the average particle size D50 was compared. The specific surface area, morphology and crystal structure of the ground calcined black talc was characterized by BET, SEM and XRD. The kinetic models of the -1μm particles in the product are also been studied. The result shows that the zirconia is superior to aluminia as grinding media, and ethanol is a better grinding aid for calcined black talc compared with triethanolamine and sodium hexametaphosphate. The D50 of product can be 1.09μm within 15min. No agglomerations between fine particles are formed in the product. The (220) is the most unstable crystal plane. Kinetic models of calcined black talc in a planetary mill under dry superfine grinding conditions using zirconia as grinding media with and without ethanol can be expressed as and respectively.

This paper studies the impact of size interval, mill rotation, media size and grinding aids on the form of kinetic and the breakage function by ultraifne grinding calcined black talc ofD97≤45μm in a CJXXM planetary mill. The results show that for the minerals ofD97≤45μm, the suitable particle size ratio which can be applied in the form of the ifrst order kinetics is 15.67. The rotational speed corresponding to maximum breakage function of calcined black talc is 1200r/min. The breakage rate is the power function of media size, the form of the power function isk=0.26843d-0.14478. Grinding aids can improve the breakage rate function, and the liquid grinding aids like triethanolamine and ethanol have a better effect than solid state grinding aid such as hexametaphosphate.

Energy consumption is a problem in ultraifne grinding process. This paper studies the impact of energy consumption onD50 and size modulus of product by wet ultraifne grinding GCC in a horizontal MiniZeta stirred media mill with different grinding aids. Three energy consumption models are established based on MATLAB software and Rosin-Rammler distribution model, and veriifed under grinding conditions with no grinding aids, sodium hexametaphosphate and Acume 9300. The results show that the value ofD50 and size modulus ifrst reduced and then stabled at certain values with the increase of energy consumption. Adding grinding aids is conducive to obtain the finer product with low energy consumption. Acume 9300 is superior to sodium hexametaphosphate for its outstanding performances in grinding and energy saving. The models established are W=0.9115a-1.4479,W=0.4532a-1.1482,W=0.6081a-1.4811 for three grinding conditions. The models are reliable after veriifed by experiment.

This paper introduces the structure and working principle of ultrafine stirred mill,analyzes its history of development and research status at home and abroad,and proposes the trend of its future development.

针对目前选煤厂生产数据报送采用电话联系方式,导致效率低、速度慢、时效性差和容易出现误报等问题,提出采用LED电子屏和计算机技术实现数据的采集、传输和岗位显示,通过现场实际应用表明,该系统自动化程度高,数据传输准确、可靠、及时,有助于选煤厂的生产调度管理和对设备的操作,值得推广应用。

According to the technical demands of the pilot production line process which uses the horizontal centrifugal separator of laminar flow to separate the low-grade diatomite,this paper studies the control scheme using the Delta PLC and touch screen technology,develops the relevant control program and monitor program,and optimizes the controlling system software through the on-line debugging.The practical application shows that the control system is stable and reliable with the high degree of automation and easy adjustment of the technical parameters,and it lays a foundation for carrying out the optimum condition experiments to separate the diatomite in the pilot production line.

卧式离心脱水机是选煤厂用于末精煤脱水的主要设备。主要介绍VM1400型卧式振动离心机的结构和工作原理,并建立动学模型对其动力原理进行分析,通过振动系统微分方程,对其振幅进行具体计算分析,得到对地基的无动负荷振动频率。

The inchoate algorithm for the coal slime flotation control is the feed-forward control to the feed concentration and the reagent quantity. This control model is widely utilized because of the easy realization once the used sensors are reliable. However the control results are usually not so good as it cannot adapt the quality fluctuation of the feed, obtain the on-line quality of the feed and the products, and also cannot statistically calculate the flotation recovery and other production management information. The appearance of the coal slurry ash detector provides the new method for resolving the problems above. This paper studies how to increase the production rate and decrease the reagent consumption through the optimizing control under the premise of the accepted concentrate ash. The industrial application of the intelligent and optimal control of the coal slime flotation results in a high concentrate recovery and a decrease of the reagent consumption, ensuring a highly efficient operation.

介绍了采用Origin8.0软件绘制原煤可选性曲线的方法步骤,分析了如何应用绘制的可选性曲线查询数据和输出图形,为教学、科研及工程技术提供技术支持。