水力旋流器在铜炉渣磨矿分级工艺中的应用

铜炉渣的磨矿分级作业存在分级浓度高、要求分级粒度细、磨矿负荷高的特点,新型旋流器通过控制旋流器进料紊流和阻力、减少溢流管处短路和控制分级空间等方面的优化,改善了旋流器的分级流场,提高了旋流器的分级效率,并在一定程度上可以提高磨机的磨矿效率和降低能耗。在铜炉渣磨矿分级中的应用实例表明,结构优化后的水力旋流器对铜炉渣磨矿分级工艺的发展有着积极的促进作用。     

提高Ⅱ段磨矿旋流器分级效果的生产实践

主要针对Ⅱ段磨矿分级作业旋流器在应用过程中存在的问题，通过开展系统除杂研究、给矿变频控制以及新型旋流器试验等措施，稳定了旋流器工作状态，提高了旋流器分级效率，同时也改善了Ⅱ段磨矿效果，优化了各项生产技术指标。     

大型高效旋流器在金矿高浓度分级工艺中的应用

某金矿一段磨矿分级使用FX660-GT旋流器，由于其结构老旧、分级浓度高等，造成旋流器溢流粒度组成不合理、分级效率低、循环负荷大等问题。针对这些问题，重新设计了大型高效旋流器FX840-GX,重点优化了旋流器尺寸、进料体结构、锥体结构、溢流管结构和旋流器内衬材质等。应用结果表明：FX840-GX旋流器能够有效改善金矿一段磨矿分级旋流器的分级效果，其中溢流中+0.180 mm占比降低了1.38百分点，分级效率提高了6.70百分点，循环负荷降低了89.79百分点，应用效果较好。     

某锡铜矿分级筛分设备的应用实践

本文介绍了螺旋分级机、水力旋流器及德瑞克细筛的工作原理及在某锡铜矿一段磨矿分级中的应用情况。分析比较了螺旋分级机及水力旋流器+细筛作为一段磨矿分级设备的的优缺点及应用特点。结果表明,细筛+旋流器的组合分级精度高,且分级效率比螺旋分级机高,对减少矿石过粉碎、降低磨矿成本具有重要的意义。     

基于SAB磨矿智能系统的旋流器结构优化与运用

城门山铜矿二期选厂在智能化矿山建设中,开发投用SAB磨矿智能系统,并在长期的生产实践中,不断优化SAB磨矿智能系统,利用其系统高效协同的优势,稳定磨矿工艺流程。本文基于SAB磨矿智能系统的应用对磨矿产品粒度组成进行分析,对旋流器结构展开研究,通过优化旋流器结构,稳定磨矿产品粒级,提高磨矿分级效率,为浮选流程创造了更佳的作业条件,在一段磨矿分级研究、旋流器的运用推广等方面具有参考价值。     

一段磨矿分级采用水力旋流器替代螺旋分级机的应用研究

针对云南某多金属选矿厂一段磨矿分级效率低,溢流细度提升小的问题,采用水力旋流器替代螺旋分级机。经过小试和工业优化试验,最终确认了采用FX500-GX旋流器作为一段分级旋流器。试验结果表明,使用旋流器替代螺旋分级机后,磨矿效果和分级指标有明显提升。磨矿分级设备均可通过DCS自动化控制系统控制,提高了磨矿分级工艺流程的稳定性,最终磨矿产品粒度组成更加均匀,过粉碎减少,为后续作业创造了良好条件。同时,球磨机平台噪声分贝有明显下降,有利于减少现场操作员工的职业健康危害因素。     

FX660旋流器组优化升级试验研究

银山矿业6500t/d铜硫选矿厂一段磨矿系统采用SABC流程,磨矿分级作业采用8台FX660旋流器(4开4备),该系统投产以来,随着生产的逐步稳定,磨矿系统台效由投产初期的270.8t/h提高到300t/h,旋流器溢流中-74μm级别含量达到65%以上,但+178μm级别含量达到9.36,略高于计划要求。为了降低旋流器溢流中+178μm级别的含量,对FX660旋流器进行优化升级,采用蜗壳预分级进料体新结构旋流器,同时对旋流器溢流管和沉砂嘴直径进行调整,将旋流器溢流中+178μm含量降低了3.02个百分点,-74μm级别提高了1.85个百分点,旋流器分级效率提高了1.77个百分点。分级作业返砂比降低了29.23个百分点。     

旋流器串联分级在磁铁矿选矿中的应用研究

为了解决细粒级磨矿的分级问题,在磨矿分级回路中,以串联旋流器组作为分级设备,提高了磨矿浓度和效率,达到了磁铁矿磨至-0．043mm的目的,使高质量铁精矿生产获得成功。     

浅析南芬选矿厂水力旋流器替代螺旋分级机的应用实践

通过对比水力旋流器与螺旋分级机的工作原理和特点。介绍了南芬选矿厂采用水力旋流器替代螺旋分级机进行分级的实践情况,实践表明了该磨矿分级系统的溢流细度、分级效率、循环负荷、磨矿效率等均有显著提高。     

提高厂坝铅锌矿磨矿细度生产实践

通过对厂坝铅锌矿磨矿分级作业的考查分析,改变了分级用旋流器参数不合理的现状,降低了旋流器的分离点d_(50),提高了磨矿细度和磨矿机的利用系数,同时也提高了铅锌回收率指标。     

When a physician makes a mistake

Inevitably, doctors make mistakes in the normal course of providing care. Making a mistake often causes distress for the doctor involved, but it can also be an important source of knowledge and self-reflection. This article discusses central aspects with respect to mistakes and medical malpractice. The doctor's relationship to ethics and legislation is discussed, and an overview of the administrative action taken by the Norwegian health authorities is presented. The organisations and offices a physician may come into contact with when involved in a patient's complaint are briefly presented. "Meldesentralen" was formed in 1993 by the Norwegian Directorate of Health for the purpose of collecting reports on accidents in medical practice. We argue that the accidents reported to "Meldesentralen" do not reflect the true situation on this issue. We introduce a model for a systematic approach towards a colleague who has made a mistake or who is suspected of having made one.     

Mixing of a Rosette Jet Group in a Crossflow

Partially treated wastewater is often discharged into coastal waters through an outfall diffuser fitted with clustered ports on risers. On each riser the effluent is discharged through two to eight ports arranged circumferentially, in the form of a rosette-shaped buoyant jet group. The near field mixing of such a jet group in a tidal flow is determined by the merging and interaction of coflowing, oblique-flowing, cross-flowing, and counterflowing jets. Despite numerous studies, a general predictive method for such complex jet groups has not been reported; ocean outfall design is often based on comprehensive physical model experiments. The mixing of merging nonbuoyant and buoyant jets issuing from a rosette outfall riser into an ambient current is studied experimentally by using the laser-induced fluorescence technique. Detailed cross-sectional measurements of the scalar concentration field downstream of the bent-over jets are made. The trajectories of multiple and individual jets discharging at various angles are measured. For typical outfall designs, the dynamic interaction of adjacent jets is found to be negligible. The average dilution of the jet group can be predicted by accounting for jet merging and plume overlapping. Theoretical predictions using the Lagrangian VISJET model are in excellent agreement with the experimental data and also results of previous studies in a stratified crossflow. The model correctly predicts the changes in near field dilution as a function of the number of nozzles on a riser, or the number of risers on a diffuser, and helps to resolve observed anomalies in previous studies.     

How a Bill Becomes a Law.

This reprinted article originally appeared in The Retired Officer Magazine, 1969, 25[3], 18-21. The first 2 lines of every bill introduced in Congress reads: "Be it enacted by the Senate and House of Representatives of the United States of America in Congress assembled . . ." Why this is so is stated in Article I, Section 1, of the Constitution of the United States, which provides that: "All legislative powers herein granted shall be vested in a Congress of the United States, which shall consist of a Senate and a House of Representatives." The article summarizes the legislative process in the US Congress, beginning with the introduction of a measure that may be either a bill or a resolution, action in Congressional Committees, committee hearings, action in the House, Senate action, conference action, Presidential action, and publication. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Vascular anastomosis using a biodegradable device with a heat-shrinking sleeve: a preliminary report

PURPOSE: The objective of this study is to present a simple mechanical anastomosis system capable of uniting vessels of differing diameters and to evaluate its applicability. MATERIALS AND METHODS: A new mechanical system for anastomosis of small vessels was used in 30 rabbits to join 100 sectioned carotid arteries and jugular veins. The system is resorbable and consists of a cuff and a shrinkable sleeve. To carry out the anastomosis, one vessel end is pulled through the cuff and everted over it. The second vessel end is then slipped over the everted vessel end and the cuff. A heat-shrinking sleeve is positioned over the site and shrunk to produce permanent fixation. RESULTS: The overall patency rate of the anastomoses was 96.6% in the arteries and 93.3% in veins. Microscopically, the intima-to-intima contact sites were bridged by an endothelial layer in the first postoperative weeks. CONCLUSION: Advantages of the system include a short insertion time, simple instrumentation, a high patency rate, and resorbability. However, the method requires additional vessel length for eversion, and it cannot be used for end-to-side anastomoses.     

Adhesive Contact between a Rigid Punch and a Half-Plane via a Thin, Soft Interlayer

The contact pressure arising when a flat-ended punch is loaded against an elastic half-plane with a thin, rigid-ideally plastic interlayer is found under adhesive conditions. Slip line field theory is employed, and the local stress state in the substrate deduced in order to assess the brittle fracture strength of the material beneath the contact.     

Just a 'wee prick' with a needle

Difficulty with vascular access is a common problem in neonatal medicine and surgery. Recent advances in parenteral therapy/nutrition and manufacture of high quality intravenous lines have enabled smaller infants to survive. Thus, in the small surgical neonate, the insertion of an indwelling intravenous long line (either percutaneously or at cut down) is a frequent occurrence. This procedure is not without its complications and it is thus necessary for the clinician inserting these lines to be aware of this and fully understand the regional anatomy of the area being used. I wish to report an unusual complication which posed several diagnostic and management problems.     

Isolation of a gene encoding a developmentally regulated T cell-specific protein with a guanine nucleotide triphosphate-binding motif

In this study, we describe a novel full length cDNA clone designated Tgtp that encodes a predicted 415-amino acid a T cell-specific guanine nucleotide triphosphate-binding protein (TGTP) bearing the characteristic motifs of a guanine nucleotide triphosphate (GTP) binding protein. Tgtp is expressed preferentially, if not exclusively, in T cells, and is up-regulated in both unfractionated and in purified CD4+8+ thymocytes upon TCR cross-linking. In contrast, expression of Tgtp is peripheral T cells is maintained at relatively high levels and is not grossly affected by TCR cross-linking. Antiserum generated against synthetic peptides from the predicted TGTP amino acid sequence recognized a single protein with a molecular mass of approximately 50 kDa, corresponding well with the computed molecular mass of 47 kDa. The only known relative of Tgtp is MUSGTP, which is reportedly expressed in B cells and bears a GTP binding motif. Thus, the discovery of Tgtp resolves a subfamily of molecules with GTP binding motifs and apparent lymphoid lineage-restricted expression. Given the restricted expression pattern in T cells, the up-regulated expression observed in response to TCR signaling in immature thymocytes, and the presence of the motifs characteristic of GTP binding proteins, we suggest that TGTP may have an important function in T cell development and/or T cell activation.     

Valuing a practice for a partnership

The hot topic from Capitol Hill in Washington to Capitol Hill in Jefferson City is health care reform. President Clinton started the ball rolling during the campaign in 1992 by including health care reform in his platform. He continued the effort after his election by appointing his wife, Hillary, to chair a task force to present an outline for federal legislation. Since the package was presented to Congress, there has been much discussion, lobbying, and rumoring about the implications of health care reform and what it could mean to all of us as dentists. On the home front, Governor Carnahan has introduced legislation in Missouri to reform the health care system. This effort is known as the Missouri Health Assurance Plan (H.B. 1622). Missouri Dental Association members are vitally concerned about the impact of health care reform on their practice, their taxes, their relationship with their patients and employees, and on their ability to seek out health care services since each member is also a consumer of health care. This article represents answers to some of the questions being asked by MDA members in order that they might be more aware of the activities by the MDA, the ADA, and other levels of organized dentistry relating to health care reform.     

Spreading of a Gravity Current over a Permeable Surface

Plane inertial gravity currents running over horizontal permeable surfaces are studied. An analytical simple model based on local and global balances is derived which describes the propagation and infiltration of an incompressible dense fluid on and through the surface. Results of laboratory experiments are presented which are in accordance with scaling laws suggested analytically. It is found that the loss of mass, the velocity, and the position of the front of the current follow exponential relationships. The dynamics is governed by a particular decay time related to the initial volume released and reduced gravity g0′. However this decay time exhibits a different functional relationship from that obtained for currents evolving over thin permeable bottoms when the downward flow is viscous. As a consequence of the loss of mass, the distance to extinction of the current is found to be independent of g0′.