NEW DRAINAGE DEVICE FOR CVRD IRON ORE CARS

Transcription

1 NEW DRAINAGE DEVICE FOR CVRD IRON ORE CARS Cristiano Jorge¹, Edilson Jun Kina¹, Solimar Boldt², Dennis Lemos² ¹Railway Engineer, ²Wagon Technician CVRD Companhia Vale do Rio Doce SUMMARY CVRD operates two of the most efficient heavy haul railroads in the world, EFVM and EFC. To support this efficient operation, CVRD has several research and development teams working on many track and rolling stock maintenance projects. One of these is a new drainage device using polyurethane, developed by CVRD Logistics Operation Department that aims to solve a serious drainage problem affecting CVRD- EFVM iron ore gondol cars (GDE). This device has been tested over three years on EFVM and its performance in several tests was excellent. From September 2005, EFVM wagon workshop started to install this device on all GDE cars in the fleet, totaling 11,300 active units, and intends to buy new GDE cars with this device installed. This paper describes the full process involved in the development of this drainage device, from its first laboratory test until its approval through to implementation on CVRD-EFVM gondol car fleet. Also, this paper will show the expected benefits from this drainage device. INTRODUCTION CVRD is the largest diversified mining company of Americas, and to transport the iron ore from its mines to port, it uses two excellent heavy haul railroads, EFC (Carajas Railroad) and EFVM (Vitoria a Minas Railroad), located in the north and southeast region of Brazil (Fig. 1). EFC Several conflicts arose between these departments involving many factors including: iron ore moisture content, ballast contamination, high track stiffness, iron ore spillage and delays in making up trains. These aspects and reasons for them will be covered in detail. After many studies and research, in 2002, the GADMG (Maintenance Development Management from CVRD Logistics Operation Department), together with VIMAX (manufacturer), developed a drainage device made from injection molded nonstick polyurethane plate, with excellent performance during three years of laboratory and field tests. EFVM Figure 1: CVRD Heavy Haul Railroads Both regions have tropical weather with rainy periods, and the presence of rainwater, during the transportation of iron ore, became a headache to many engineers that work in CVRD units in the Mine, Railroad and Port. 1. REASONS FOR DEVELOPMENT OF AN EFFICIENT DRAINAGE DEVICE The reasons for development of a drainage device for CVRD-EFVM Iron Ore Gondola Cars were: 1.1. Rain water In Brazil s southeast region from November 2002 to February 2003, CVRD engineers established a close relation between heavy rainfall and the increasing number of accidents for EFVM freight transportation. And this was also the case in and Trains traveling on EFVM during rainy period, both loaded and empty cars collect a large amount of rainwater. 59

2 This increases the weight of cars (1.6 tons per GDE car) and consequently increases fuel consumption (typical EFVM iron ore train consists of 2 locomotives & 160 cars or 3 locomotives & 240 cars). The lack of drainage results in a swimming pool of water in the case of empty cars (Fig. 2) or iron ore spillage over the top of loaded car (Fig. 3). Undetected and moving onto mainline operation the rechego (load on one side of car and an increase in the centre of gravity) can prevent the bogie from rotating freely and cause the car to derail in sharp curves when traveling at 65 kph (Fig 6.). Figure 2: Swimming pool in empty car Figure 4: Rechego on one side of the GDE iron ore car after dumping Figure 5: EFVM Rotary Car Dumper Figure 3: Iron Ore spillage from loaded car 1.2. Ballast contamination In the past, drainage was achieved using a number of small holes in the car floor. This resulted in some iron ore passing through these holes and spilling onto the ballast. The iron ore fouling the ballast created a stiff track support with poor drainage. Consequently, EFVM Corridor General Management decided to close these holes to prevent ballast contamination. This in turn created other problems: the rechego formation and an increase in iron ore moisture content Rechego formation Rechego is the Brazilian term describing the wet compacted iron ore that adheres to one side of the car during rotary dumping (Fig. 4). This product can stay with the car if not detected. At times the Car Dumper (Fig. 5) requires 4 or more attempts to release the retained product (rechego). Figure 6: Derailment caused by rechego presence in the empty iron ore car 1.4. Alteration of iron ore moisture rate The large amount of water collected by the iron ore car increases the moisture content of the iron ore above the limits set by the customer. This increase in iron ore moisture content measured at the Mine and the Port results in penalty payments. 60

3 2. THE POLYURETHANE FILTER 2.1. Characteristics Drainage filter, made from injection molded non-stick polyurethane fitted into a steel frame 390 slits (0.4 x 12.4 mm) Length x Width x Height =277x127x31 mm 4 units installed per iron ore car Held by snap fit (at 4 points) High resistance to iron ore compression High resistance to iron ore abrasion High resistance to hydrolysis Hardness = 90 Shore A No clogging of the slits 2.2. Functions Efficient water drainage Efficient iron ore retention Reducing the iron ore moisture content 2.4. Pictures of the Drainage Device Figure 10: Steel ASTM A242 filter frame & Polyurethane Filter 2.3. Drawings 31mm 127mm Figure 11: Polyurethane Filter (lower view) 277mm Figure 7: Polyurethane Filter Points of Pressure Figure 12: Four filters installed in the GDE car Figure 8: Steel ASTM A242 filter frame to be welded in the floor of the iron ore car Filters Figure 9: Filter Position on the GDE car Figure 13: Filter installed in the GDE car (below floor view of filter frame) 61

4 3. LABORATORY TESTS The CVRD laboratory tested the permeability of several types of iron ore mines from its South System and retention by the filter system Pictures of laboratory tests 3.1. Equipment Metallic box with filter to simulate the iron ore car Containers to collect water and equipment to remove iron ore from the box 3.2. Procedures PRO-1: To simulate the typical tropical rainy weather during a loaded train travel on EFVM, it was necessary to insert a given type of iron ore in a metal box, and after, add water in excess. PRO-2: The iron ore and the water were added in inserted way (i.e. one amount of iron ore plus one amount of water, later more amount of iron ore, more amount of water, successively) until complete the metal box with water in excess. It can observe that in the PRO-1, the water wad added in iron ore surface, simulating that the rain started after iron ore loading, during the travel. In the PRO-2, it s raining during the iron ore loading (iron ore is saturated in the travel beginning). In the moisture test, the iron ore was at rest, and the responsible person stayed observing the water volume collected. The objective of the drained water solid percentage test was to evaluate the iron ore retention capacity of the polyurethane filter. Figure 14: Internal view of metallic box with polyurethane filter installed at the bottom Figure 15: Metallic box with iron ore PXGS after addition of excess water 3.3. Classified Types of Iron Ore CVRD-EFVM trains transport several classifying types of iron ore from the mines to port (144 classifications based on origin mine, grain size, iron rate, and customer request). The engineering team collected information of the more problematic iron ore types with high water retention. The main criteria were difficulties dumping the ore and high moisture content. The following table shows the worst types of iron ore to be tested: Table 1 Worst types of iron ore Code Name Pellet feed special from PEGS Gongo Soco Mine Pellet feed export from PXGS Gongo Soco Mine SFCA Sinter feed from Cauê Mine Sinter feed special from SECE Conceicao Mine Grain size (average) 0.40 mm 0.07 mm 2.57 mm 2.26 mm Figure 16: Polyurethane filter after permeability test with iron ore SFCA 3.5. Results Table 2 Laboratory Test Results Type PRO Final Moisture (%) Drained Sample (Kg) Solid Percentage (%) PEGS PXGS SFCA SECE

5 The most part of water had absorption by iron ore, with differences according to type of iron ore. After excess water was added (close to saturation), the water runs through iron ore voids and reaches the filter, passing through it. The drainage time varied with test procedure and type of iron ore. PRO-1 took more time to drain than PRO-2. Drainage time in service improved due to car body vibration on track. The filter was efficient, passing large amounts of water with practically no clogging. These results indicated the importance of the top drain holes (Fig.17), located on the top of front and rear walls of car body. These allow faster drainage of surface water and avoid water having to saturate the iron ore before passing through to the filter. Figure 18: GDE car with polyurethane filters installed for field test on EFVM 4.1. Collecting Box GDE car was fitted with a collecting box (Fig. 19) covering the outlet of one of four filters. Its purpose was to collect material passing through the filter slits. The characteristics of the collecting box are the following: Figure 17: Drain Holes located on the top corner of GDE car box Prototype testing of the drainage device produced excellent results providing sufficient justification to proceed to more extensive in service testing and evaluation. 4. FIELD TESTS Following laboratory testing, four filters were installed in each of two experimental GDE cars (numbers and ) (Fig.18). Two GDE control cars without filters ( and ) were coupled to the first ones to establish a comparative performance. Figure 19: Collection box installed on the GDE Raw material: Cast iron Length = 300 mm Width = 300 mm Height = 200 mm Volume = 15,980 cm³ Format = Cubic with 4 drain holes in the upper part of side walls (2 holes on opposite sides), to limit water level to a maximum height of 160 mm. In this case, the solids passing through the filter will remain in the bottom of the collecting box, while excess water pass through the overflow holes. 63

6 4.2. First Field Test In March 2002, the four GDE test cars were coupled into a train at CVRD Industrial Complex in Vitoria. The objective was to operate on EFVM for six months under the same transport conditions as other GDE cars in the CVRD-EFVM fleet. After this period, in October 2002, the cars were taken to EFVM wagon workshop for a first inspection (Figs. 20, 21 and 22). Figure 22: Exterior view of polyurethane filter No clogging of the slits Figure 20: View inside the car during first inspection Figure 21: Closer view of the polyurethane filter during first inspection after six months After inspection, the test cars were returned to service on EFVM. In 2003, four more inspections were carried out as described in the following section Inspections after Field Test The purpose of inspections of GDE test car with polyurethane filters was to evaluate filter performance in relation to: Resistance to mechanical loading from 75 tons of iron ore covering the GDE box floor including the four filters for the duration of the Mine-Port trip in a EFVM iron ore train Resistance to abrasion, caused by aggressive action of iron ore when sliding over the car floor and filters Material quality, checking for wear and structural damage (fractures, holes, etc.) Efficiency of water drainage in the GDE iron ore car Following the three first inspections, carried out in January and May 2003, it was found that the filters remained in good condition, without damage and without clogging Specific Test In August 2003, specific tests were conducted to evaluate the iron ore retention using the four worst types of iron ores determined by the laboratory tests. The first one was the SECE (Sinter Feed Special from Conceicao Mine). When the iron ore train arrived in the Caue Mine, the GDE test cars were loaded with SECE. A large amount of water was added with a hose to completely fill the GDE car. The purpose was to simulate the worst travel conditions during rainy periods that commonly occur between November and February (Fig ). 64

7 Figures 23 to 28: SECE Loading of GDE test cars with filters and addition of water to simulate heavy rain along EFVM Results from Specific Test The collecting box was removed before arriving at the Cardumper. The purpose was to collect the solid sample volume that passed through the filter. This sample was sent to the laboratory for grain size analysis. Filters performed the drainage function with a low (insignificant) percentage of iron ore fines passing through. For each filter there was a loss of g of iron ore giving a total of g per GDE car Other Specific Tests and Results The same procedure was used in 2004 to perform in service testing with three more problematic iron ore types (SFCA, PEGS and PXGS). The results were the same regarding structural performance of filters without damage. The results for iron ore lost are summarized in the following table: Table 3 Specific Field Test Results Type Iron ore lost per GDE car (kg) Reasons for loss After dumping, the empty GDE test cars with filters were sent for inspection in the wagon workshop. The results obtained were: The filters remained in good structural condition and without damage No clogging was found and there was no material covering the filters No change in filter slit dimensions and no deformation SFCA 3.2 PEGS 0.3 PXGS 0.2 Water washed fines from the SFCA particles and carried these through many voids and past the filter Tri-axial compression and absence of voids, prevents the loss of small particles with grain size smaller than filter slit size 65

8 5. EXPECTED BENEFITS The benefits expected are as follows: 5.1. Reduction of train fuel consumption, through prevention of swimming pools formed in the empty GDE cars during rainy weather. This represents a water weight saving of approximately 1.46 tons per wagon (remember that EFVM iron ore trains have 160 or 240 GDE cars). Using TEM Train Energy Simulator it is estimated to safe more than 4% of fuel consumption per year 5.2. Reducing iron ore train cycle time, through elimination/reduction of rechego during Cardumper operation 5.3. Maintaining iron ore quality, due not changing of the moisture content 5.4. Increasing useful life of car components, through weight reduction of both loaded and empty GDE cars during rainy weather 5.5. Elimination of ballast contamination, because filters minimize loss of iron ore from GDE cars 5.6. Improving EFVM operational safety, through reduction of accidents caused by excess water in the car 6. INSTALLATION SCHEDULE ON EFVM The installation of polyurethane filters in GDE cars was started in November 2005, completing this process for the GDE fleet in February 2007, totaling 11,300 GDE cars. The physical schedule, financial schedule and project budget are shown, respectively, in Tables 4, 5 and 6. The work to be accomplished will involve 4 shifts of 6 people, totaling 24 people installing the filters (with 1 team off duty) 7 days per week. Therefore, the filters will be installed at a rate of 800 GDE cars per month. Table 4 Physical Schedule of number of GDE cars with filters to be installed Number of GDE Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb with filters Table 5 Financial Schedule of cost for GDE cars with filters to be installed Budget * 2007 * Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb (*) 30% Added in Polyurethane and Steel values from April 2006 to February 2007 Table 6 Project Budget (USD) Description Amount per GDE car Unit Value (USD) Total Value 2005/6 (USD) Total Value 2006/7(USD) Polyurethane Filter Steel ASTM A242 rack box Work force contracted Material (welding, gas, machine rent, painting) Subtotal per GDE car (USD) EFVM fleet of GDE cars 2,900 8,400 Total Value for entire GDE fleet with filters (USD) 2,540,

9 7. FORECAST ECONOMIC RESULTS The fuel consumption simulation by TEM Train Energy Simulator resulted in minimum reduction of 3.6% of fuel per year. Considering the three rainy months, EFVM will must safe more than 500,000 liters of diesel. Only this fuel safe during a horizon of 6 years is sufficient to cover the installation costs (payback period) and a minimum Net Present Value (NPV) = USD 88,155.00, becoming this project economically viable to CVRD Logistics Operation Department. The other tangible benefits as reduction of iron ore train cycle time and increasing of useful life of car components will extend considerably this NPV. 8. CONCLUSION Many types of drainage systems could be applied to iron ore cars. The CVRD research team investigated many different materials such as stainless steel, hard plastic, cast iron, etc. However, it was important to use a material with sustainable cost benefits as it was to be installed in more than ten thousand cars. Polyurethane was chosen for its mechanical properties in order to resist abrasion and compression from iron ore inside the car. The polyurethane filter performed these functions with excellent results. During the next 13 months, the CVRD team will be installing this drainage device in all of the EFVM GDE car fleet. Also, in parallel, this device is to be tested in our other heavy haul railroad EFC located in the north of the country and to start installation at the beginning of This will include more than seven thousand EFC iron ore gondol cars (GDT). In conclusion, it will be necessary to monitor this project for one year after installation to measure the performance and evaluate the benefits provided by this new device to ensure that it will satisfy the project objectives. 67