資源目錄里展示的全都有，所見即所得。下載后全都有,請放心下載。原稿可自行編輯修改=【QQ：401339828 或11970985 有疑問可加】 ImEnnnlI0na1 Jmlml OF mmuwh PttocE5smG Int. J. Miner. Process. 44-45 (1996) 461-469 New comminution applications using hydrocone crushers with setting regulation in real time Arvid Svensson, Per Hedvall, Max Fjaestad Allis Mineral Systems, Crushing and Screening, Svedala, Sweden Abstract The setting (distance between mantle and concave ring) of the Hydrocone cone crusher is altered, even with the crusher operating at full load, by lifting or lowering the mantle by means of a hydraulic piston (Hydroset). Modem developments in the field of electronics and microcomput- ers have made it possible to design a small, reliable and very sophisticated system for automatic regulation of the setting of a Hydrocone crusher. The system monitors energy consumption, crushing force and setting and continuously adapts the crusher to even small variations in the feed and/or operating conditions. This technology has expanded the range of applications that can be successfully solved with cone crushers. In the paper we will give a general description of modem cone crusher technology and also give some examples of new possible applications. Fine crushing in closed circuit with a screen can, thanks to automation and carefully designed crushing chambers, compete with rod mills. Products smaller than 3 mm are common. Another example is the crushing of a gold ore to - 10 mm, in open circuit, with a Hydrocone crusher. The automation system ensures that the crusher runs at the smallest possible setting and thus ensures that the correct discharge is produced. In some applications it is interesting to operate cone crushers in a wet process. About 20 years ago, Allis Mineral Systems installed the first Hydrocones with water injected together with the feed. These crushers are still in operation and we will present our experiences. Small flexible cone crushers with computer control can be used to create more cost efficient ore crushing plants than the conventional installations with few large machines. The “crushing cassette” idea is presented. 1. Introduction The Hydrocone crusher is characterised by the hydraulic support of the mainshaft. The setting of the crusher (often called CSS, closed side setting) can be adjusted by moving the mainshaft up or down. The eccentric assembly forces the mainshaft in a gyrator!, (not rotating!) movement creating the crushing action between the concave ring and the mantle. See Fig. 1. 0301-7516/96/$15.00 0 1996 Elsevier Science B.V. All rights reserved SSDI 03 31-75 16(95)00052-6 462 A. Svensson et al./Int. J. Miner. Process. 44-45 (1996) 461-469 Fig. 1. Principle for Hydrocone crusher with ASR-plus. The concave ring and mantle are consumable wear parts made from abrasion resistant manganese alloyed steel. The shape of the profile of these liners are essential for high constant production in terms of capacity and reduction. The ideal profile is depending on the size and distribution of the feed particles, among other things (Svensson and Steer, 1990). In order to live up to a wide variety of applications, the Hydrocone crusher has seven different crushing chambers from extra coarse to extra fine. 2. Automatic setting regulation- ASR Allis Mineral Systems (AMS) have manufactured automatic setting regulation (ASR) systems for Hydrocone crushers since 1968. The first types were based on relays and had slow regulation and simple logic. They monitored motor power, hydraulic pressure and oil level in the Hydroset tank (indirectly mainshaft position). The systems were refined and in 1986 after producing 1550 units the computer based ASR-C was introduced. The unit had faster regulation and more accurate control allowing it to adjust the setting of the machine at very tine intervals (0.1 mm). This gave a new and unique opportunity to run the crusher at a selected maximum hydraulic pressure and motor power allowing the automation to find the corresponding “ideal” setting. With feed variables such as work index, granulometry, moisture content etc., constantly changing the “ideal” setting for the crusher will also change. In older designs, a fixed setting was chosen and then the hydraulic (or mechanical) pressure and A. Svensson et al./lnt. J. Miner. Process. 44-4.5 (1996) 461-469 463 consumeId power were allowed to vary. Depending on setting, this leads to frequent overloadmg of the crusher or low power utilisation i.e. inefficient crushing. With difficult feed materials, such as moist ores with clay contamination, both may occur! The cNoncave ring and mantle get worn with use. This means that the setting between them increase due to this. A manually operated crusher must be calibrated to compensate for this. A crusher running with power and hydraulic pressure as guide will not encounter this problem, the setting is automatically adjusted. With abrasive materials, like gold ore or quartzite, the crusher setting can increase 1 mm due to wear in a single shift. If this happens in a fine crusher running at CSS 6-7 mm, the relative impact is drastic. In 19 22, the ASR-C was replaced (after 500 units) with the ASR-plus. This system is quicker and has a better, adaptive regulation algorithm. It is easier to programme and has a colmputer communication interface (RS-485) included as standard. Via a telephone modem and a PC we have the possibility to reprogram an ASR-plus system from long distances. The ASR-plus has a memory which can store five different crushing “recipes” and also data on the performance of the crusher. Some of the 249 variables that are available are: CSS, CSS setpoint, average CSS during given period, same for min and max CSS, power, max power, pressure, max pressure, wear, % remaining of total mainshaft travel, regulation modes for 5 recipes, regulation damping for 5 recipes, total and loaded operation time since new, same since latest liner change, same since latest calibration, energy consumption and total pump time. 3. Fine crushing Traditionally crushers have been used for production of fractions down to - 12 or - 16 mm, suitable for primary grinding in rod mills. Today it is feasible to make a - 3 mm product in closed circuit or a - 10 mm product in open circuit. By u,sing controlled feed analysis, optimised crushing chamber and ASR it is possible to create a pressure zone in the crushing chamber leading to interparticle crushing. Some factors to consider are: 3.1. Feed granulometry It is important that the crushing chamber has sufficient intake opening to swallow the largest particles in the feed with great ease. The feed fraction must also have sufficient amount of voids to avoid packing. 3.2. Work index The hardness of the rock is measured by the Impact Work Index test method developed by Mr. Fred C. Bond of Allis Chalmers (today Allis Mineral Systems). This method is based on particles from 50 to 75 mm and has no correlation to the Grinding Work Index method developed by the same man. In general, we assume that soft rock like lim.estone has WI = 12, medium hard rock like granite has WI = 16 and hard rock such as basalt has WI = 20 (kWh/tonne). 464 A. Svensson et al./Int. J. Miner. Process. 44-45 (1996) 461-469 3.3. Density A conecrushers act similarly to a piston pump in the sense that it crush on a certain volume of rock for each revolution. This means that a heavy rock will have a higher capacity than a comparable one with lower density. 3.4. Moisture The moisture in the feed will be absorbed evenly on the particle surfaces. In practice this means that most of the moisture will be absorbed by the finest particles and increase their adhesion to each other and the crushing surfaces. This means that capacity will drop with increasing content of moisture and with decreasing setting. See Fig. 2. 3.5. Choke feeding For a cone crusher to work in a relatively steady state, it must be choke fed. This means that the volume above the crushing chamber always is full of material which flows into the crushing chamber at a pace decided by the crusher. See Table 1 and Fig. 3. 3.6. Distribution If the feed material is segregated on entry to the crusher, the crusher will have to adjust to the area of the chamber where the most difficult crushing takes place. The rest of the chamber will get the same setting and thus not work to its full potential. The chamber will be partly choke fed and partly starve fed. 3.7. Example of performance from a fine crushing circuit A fine crushing circuit as shown in Fig. 4 can accept a feed of 4-12 mm of dry gold ore and make around 50-55 mtph of - 4 mm product using an installed power of 132 kW. Fig. 2. Capacity reduction due to moisture content. A. Suensson et al./Int. J. Miner. Process. 44-45 (1996) 461-469 465 Table 1 Importance of choke feeding a cone crusher. Crusher: Hydrocone H-36-M, throw 32 mm. Feed material: Gneiss-Diabase. Feed size: 3-25 mm, 50% 3-9 mm CSS (mm) % css % Capacity (l/h) kWh/t -6 mm t/h -6 mm Choke fed Starved 9.5 9.5 72 56 50 34 90 45 3.9 1.8 107 77 1.67 1.73 54 27 3.8. Fine crushing in open circuit A new concept in fine crushing is to use the ASR system as a guarantee for correct final size as opposed to use a screen for this duty. The benefits are obvious, lower installation cost since no final screens or return conveyors for coarse material are needed. A practical example of this is shown in the flowsheet in Fig. 5. This is taken from a Teberebie gold fields in Ghana where the final stage is composed by two H-4000-EF cone crushers with ASR-C control systems. Each crusher is fed with 100 mtph of lo-25 and crushes this down to - 10 mm (P, = 9.3 mm) in open circuit. The crushed ore goes directly to gold benefication by agglomoration, cyanide leaching and active carbon recovery. STOP SIGNAL TO FOFlEGOlNG FEEDER 4-e -_ _ I I / -I # , nMlN. IN SURGE SIN CONTROL SIGNAL TO FEEDER MAX. IN CRUSHER FEE0 HOPPER w Ei 0” 0 aocpo 0” 0000 oq OOOO OOOO SWITCHGEAR UNIT Fig. 3. How to obtain choke fed crusher. 466 A. Suensson et al./lnt. .I. Miner. Process. 44-45 (1996) 461-469 4. Wet crushing In special applications it may be interesting to crush rock or ores in wet conditions. Normally this only takes place when the feed material already is moist or wet from a preceding process, a typical case is crushing of critical particles from a SAG or AG mill. In some cases it is interesting to actually add water to the feed prior to crushing. A typical case could be crushing of materials which cause hazardous dust. The amount of water must be sufficient to give a large quantity of free water and a absolutely soaked feed. This means that the water content is depending on the type and granulometry of the feed. In general we use between 0.75 and 1.5 cubic meters of water per tonne of feed material. In general the following points apply for a wet crushing process with Hydrocone crushers: * Capacity through the crusher is increased due to transport of fine material by the water flow. . The power consumption for a given setting is comparable to that of a dry process. . The discharge product contains less fines in comparison to a dry process. CONE CRUSHER ;m?Mx t-3UOO-EF EXTiEM F/G CRUWI. ASRpl us O-f mm Fig. 4. Flowsheet of fine crushing circuit with H-3000-EF. Fig. 5. Flowsheet from Teberebie Goldfields, Ghana. A. Svensson et al./Int. J. Miner. Process. 44-45 (1996) 461-469 461 2xH-84 3 x H-4000 Motor power (kw) 2 x 300 = 600 3 x 200 = 600 I Crusher weight, incl. - 85 500 each - 17 250 each motor & sub-frame (kg) I I Heaviest Iii (kg) - 28 100 - 17 250 I Relative investment incl. motors, starters, feeders, - 230 - 100 support frames, etc. -J Fig. 6. Comparison of large and small cone crushers. * The crusher can normally be operated at smaller CSS than in a dry process. . The life of wear parts are reduced to approximately 70% due to corrosion. ?The crusher is even more sensitive to feed variations and the ASR are consequently set up for very fast regulation. 5. The crushing cassette system 5.1. Small versus big crushers in large crushing plants Many crushing plants for large tonnages (500-2000 mtph) are built after the philosophy that “big is beautiful”. The main design concern has been to use as few machines as possible, leading to very large machines and simple process solutions. A new approach is a crushing plant based on smaller machines in a more optimised process, Some of the arguments for this development are: 468 A. Svensson er al./lnr. J. Miner. Process. 44-45 (1996) 461-469 Fig. 7. Schematic design of Hydrocone 4000 crushing cassette. The unit can be rolled on tracks into a service facility and be replaced by a unit with new liners. Very large cone crushers (with cone diameter of 2.1 m and bigger) represent less than 15% of cone crusher sales world-wide. This means that smaller crushers are manufac- tured in larger series and therefore can be produced more costeffectively. Small crushers generally give more crushing for the dollar. More or less the same applies for vibrating screens. See Fig. 6 (from Svensson and Steer, 1990). In a plant with a larger number of crushers the output of the plant is less dependent on each individual machine. The long-term average capacity and availability are improved. A crushing process with more machines can allow for the individual crushers to be more optimised for their duties. The main drawback with smaller machines is that they have smaller wear parts and thus need to change liners more often (the actual wear rate in grams per tonne of feed is equal or better for smaller crushers). This is compensated for by the far superior serviceability of smaller crushers. If we compare the practicality of a 84” Hydrocone A. Svensson et al./Int. J. Miner. Process. 44-45 (1996) 461-469 449 (installed power 300 kW) weighing 78 200 kg with two 4000 Hydrocones (2 X 200 kW) each weighing 14000 kg the differences are clear. The topshell (19 600 kg) and mainshaft (23 500 kg) of the big machines are heavier then the entire H-4000. 5.2. Crushing cassette Flexibility was one of the most important design parameters of the modem Hydro- cone crushers. All seven crushing chambers (EF, F, MF, M, MC, C and EC) can be fitted to the same topshell. The eccentric bushings have 3 or 4 keyways cut to provide simple change of eccentric throw. As an example we can transform a H-4000-EC (capable of crushing a - 210 mm feed) into a H-4000-EF (capable of making a product with P, = 6.5 mm from 6-12 mm feed) just by changing wear parts (mantle and concave ring). The beauty of this in a large plant is that virtually identical crushers can be installed in secondary, tertiary and quartenary stages and then after a change of liners go into work in any of the other positions. See Fig. 7. Reference Svensson, A. and Steer, J.F., 1990. New cone crusher technology and developments in comminution circuits. Miner. Eng., (l/2): 83-103.