WO2005115625A1

WO2005115625A1 - Lead feeder device for the production of lead oxide

Info

Publication number: WO2005115625A1
Application number: PCT/IB2005/051271
Authority: WO
Inventors: Armando Marfisi; Bruno Marfisi; Fernando Marfisi
Original assignee: Cam S.R.L.
Priority date: 2004-05-26
Filing date: 2005-04-19
Publication date: 2005-12-08
Also published as: ITCH20040002U1

Abstract

A lead feeder device (1) for the production of lead oxide entails no lead melting and it comprises: a line (2) for feeding lead in ingots (L); one or more cutting tools (12) scraping the surface of an ingot (L) so as to produce shavings (T) curved according to a basically helical turn; and means (18; 15a; 15b; 15c) for collecting said shavings and directing (30) the feeding of abrasion mills.

Description

LEAD FEEDER DEVICE FOR THE PRODUCTION OF LEAD OXIDE Background of the invention 1. Field of the Invention The present invention refers to a lead feeder device transforming lead ingots so as to feed the adequately transformed metal in a system for the production of lead oxide, in particular to an abrasion mill where the oxidation reaction occurs. 2. Description of the state of the art Lead oxide is a basic material necessary for the manufacturing of sulphuric acid accumulators of electrical energy, in which the lead oxide, Pb0₂ in its more general formula, combines with the acid (H₂S0₄) reducing itself. Therefore, the oxide is mass-produced, at costs that should, for obvious reasons, be kept to a minimum. Hence, large quantities of lead are treated in order to have them react with oxygen and even minimal improvements in the overall effectiveness of this process can lead to remarkable economical advantages. By way of introduction to the feeder device, the system for the production of lead oxide comprises rotary abrasion mills, made of a large cylindrical container rotating about the axis thereof, which is arranged horizontally. At one end thereof, the mill is supplied with lead reduced in granules or pellets, of a few centimetres in size, which, inside the reactor, tumble by effect of said rotation and rub the one against the other, implementing a granule-to-granule abrasion and generating heat by friction. By virtue of the air that is fed into the reactor, generally by natural draught, the oxidation reaction takes place; the latter, being a mildly exothermic reaction, is capable of self-sustaining. The air, carrying oxygen to the lead, is capable of penetrating between the lead in granules through the interstices. The granules or the pellets, which will be mentioned hereinafter, represent an evolution in the feeding of oxidation reactors that to date occurred by providing lead in ingots or cakes, entire or subdivided into four or five portions. It is understood that the reaction temperature is a decisive factor for a good outcome and a high yield of the process. It may, e.g., be controlled by virtue of burners acting on the external shell of the rotary container (heating) and of water sprayers internal to the container (cooling). The temperature may be measured by pyrometric systems, which however can measure the surface temperature of the lead mass in the mill, or by detecting the temperature of the air flow outletted from the opposite end of the mill; yet, in this case as well such a measuring can be not fully representative of the reaction temperature. Therefore, also due to the shape of the granules, not allowing an even distribution of the air in the lead mass, the temperature, inside the mass, can vary so as to make less than optimal the effectiveness of the reaction.

Moreover, an excessive increase of the temperature inside the tumbling mass in the mill leads to the formation of orthorhombic oxides, unsuitable for use in accumulators. The known feeder devices transform the lead, which is made available in the form of large-sized and elongated parallelepiped-shaped ingots or cakes.

The reduction in granules in the feeder device envisages the melting of the lead and the moulding of the granules, usually shaped as small cylinders.

This process is complex; it requires the consumption of a relevant quantity of energy and entails the risk of releasing potentially hazardous lead vapours in the environment. In particular, this kind of device requires complex systems for the abatement of lead vapours, a system for scorifying the molten lead, in turn producing slags that have to be treated as special waste, and a remarkable quantity of energy for its operation under heating. In addition, the crucible of the device at issue should be heated continually, as interruptions in the heating would lead to the solidification of the lead contained therein, ruining the crucible. Moreover, at this stage care should be paid to the problem of the microcrystalline structure of the metal and of its titration, parameters that could vary through the melting and the solidifying into small cylinders, and that could require a curing or seasoning of the lead in granules so as to have it assume the desired microcrystalline shape, suitable for the production of high-grade lead oxide. Lastly, the lead obtained with the melting device cannot be stored outdoors, as it would tend to absorb rainwater and dew, to then explode once heated. Summary of the invention The technical problem underlying the present invention consists in overcoming the drawbacks mentioned with reference to the state of the art. Such a problem is solved by a feeder device comprising: * a line for feeding lead in ingots; * one or more cutting tools scraping the surface of an ingot so as to produce shavings curved according to a basically helical turn; and * means for collecting said shavings and directing the feeding of abrasion mills. The device according to the invention entails several advantages. Firstly, the shavings can be directly used for the feeding of oxidation mills, completely replacing the forming of lead in granules, requiring no lead melting. Moreover, the shape of the shaving, appearing basically as a hollow cylinder of irregular shape and with sharp edges, helps to attain an improved air distribution inside the lead mass in the mill and a more effective friction among shavings in the mill, improving the efficiency of the oxidation reaction. Furthermore, the lead shaving is subjected to a mechanical stress giving to the metal internal stresses, of compression at the intrados of the shaving and of traction at the extrados thereof, facilitating the forming of flakes inside the mill. The shaving-shaving abrasion is enhanced, besides by the sharp edges of the shaving, also by the surface that the mechanical stress has hardened.

The external surface of the shaving, which owing to the mechanical cutting of the lead appears smooth and clean, is susceptible of being the site of chemical oxidation reactions. Hence, the above defined feeder device requires no lead melting, thereby avoiding the need of a system for abating lead vapours and treating slag.

Moreover, the cold machining of the shavings requires a lesser energy expenditure by the device, which can be stopped at any time without prejudicing its functionality. Lastly, the shavings, having undergone no modifications at a crystalline level, do not absorb water and therefore can be stored outdoors, abating storage costs. Hereinafter, the invention will be described with reference to an embodiment thereof, given purely by way of a non-limiting-example and with reference to the annexed drawings. Brief description of the figures * figure 1 shows an overall perspective view of a lead feeder device according to the invention; * figure 2 shows a top plan view, partially sectional along a horizontal plane, of the device of figure 1 ; * figure 3 shows a partially sectional perspective view of a detail of the device of figure 1 ; * figure 4 shows a perspective view of the detail of figure 3 seen from the outside of the device; * figure 5 shows a perspective view of a lead shaving produced by the device of figure 1 ; and * figures 6A to 6E schematically illustrate various examples of cutting tools that may be used in the device of figure 1. Description of an embodiment of the invention With reference to figures 1 and 2, a lead feeder device for abrasion mills, for the production of lead oxide, is generally indicated by 1. It is supplied with lead ingots L, adequately titrated and therefore suitable for the production of oxide. Said ingots L are of a basically elongate prismatic shape, with a section of isosceles trapezium form. The device 1 comprises a line for feeding ingots L, generally indicated by 2, which is supported by a support frame 3 and composed of various sections. A first section 4 receives the ingots L that are arranged transversally thereto, and comprises a first belt conveyor 5 translating the ingots L from a charging end 6 to a second section 7, at which a second belt conveyor 8 carries individually the ingots L to a third section 9 of the feeding line 2. The third section 9 of the feeding line 2 is connected to a station for cutting the lead ingots L, generally indicated by 10. While the first and the second section 4, 7 are rectilinear to the lead ingots L arranged transversally thereto, the third section 9 is perpendicular to the preceding sections, thereby receiving the ingots arranged lengthwise. Therefore, the third section 9 is channel-shaped in order to lead each individual ingot L according to a direction agreeing with the development in length of the ingot itself. For this purpose, the third section 9 comprises means for pushing the ingot 9 in the direction of the cutting station 10. The pushing means, in the present embodiment, comprises a linear actuator 11 , e.g. oleo-dynamic, acting on the distal end of the ingot L with respect to the cutting station 10. A variant of the pushing means could comprise a conveyor with cleats, spaced lengthwise of the ingot L. Though not shown in the figures, there could be first position sensors for detecting the presence of the ingot L in the third section and for operating said linear actuator 11 , and second position sensors signalling the approaching of the ingot L to the cutting station 10 and activating the latter. The latter sensors can signal the running out of ingot L in the cutting station, thereby driving the operation of the second belt conveyor 8 to feed a subsequent ingot L in the third section 9 and then to the cutting station 10. Thus, by seeing to it that the first section 5 is adequately charged with ingots L, the operation of the feeding line 2 and of the cutting station 10 can be basically automated. Of course, it is understood that also the charging of the ingots L on the first section can be specifically automated. The device 1 comprises, at the cutting station 10, a plurality of cutting tools 12 arranged so as to scrape the ingot L that is fed inside the cutting station 10 along said third section 9. In the present embodiment, the arrangement of the cutting tools 12 and of the advancing ingot L is such that the cutting tools 12 act on the proximal end of the ingot L, so as to produce shavings S curved according to a basically helical turn. The shaving T, depicted in figure 5, comprises sharp edges 51 , an external surface 52 basically smooth owing to the cutting and an internal groove 53. The thickness of the shaving T could be of >1.0 mm. The ingot L, as it is introduced in the cutting station 10, is completely cut and reduced to shavings T that fall downwards and are received in a collecting portion 18 of the cutting station 10. It is understood that the distal end 19 of the ingot L, which is pushed by the linear actuator 11 , at the end of the cutting of the ingot L will fall in the collecting portion 18 without being cut, mingling with the shavings T to be then directed therewith to the feeding of an abrasion mill. The presence of a portion of ingot L for a certain quantity of shavings T could entail a greater abrading action inside the mill. The collecting portion 18 acts as means for collecting the shavings T. The cutting station 10 comprises a containment case 13 inside which the cutting tools 12 operate. The latter are rotated about an axis perpendicular with respect to the direction of feed of the ingot L, axis that in the present embodiment is vertically arranged. The case 13 comprises an inspection door 22 for accessing the cutting tools 12. The cutting tools 12 are mounted on toolholder bars 14 so as to be easily replaced when worn out. The bars 14 project radially from a vertical cylinder- shaped shaft 15 that is driven in rotation by a ratio motor 16 mechanically connected to an electric motor 17 of adequate power. The distribution of the cutting tools 12 on the shaft 15 is such that the tools 12 cut on all the infed end of the ingot L. The feed rate of the ingot L and the rotation rate of the shaft 15 will suitably be adjusted to obtain shavings T having the desired thickness. The cutting station 10 comprises means for lubricating and cooling, which in the present embodiment uses water in order not to introduce oils that could pollute the feeding of the abrasion mills. Water is sprayed by a plurality of nozzles 20, arranged above and/or around the cutting tools 12 and fed via a duct 21. Lastly, the device 1 comprises means, generally indicated by 30, for directing the shavings T to an abrasion mill M, partially visible in figures 1 and 2. The directing means 30 comprises a conveying belt 31 mounted on a respective support frame 32, arranged tilted upward and capable of raising the shavings to a collection height. At this level, the shavings T can be stored in a container for a subsequent insertion in an abrasion mill or, optionally, could also be directly inserted in an abrasion mill M via a chute 33. In this latter case, there may be preset a control system that, on the basis of the need to feed the mill M, controls the quantity of lead in ingots that is processed by the feeder device 1. The cutting tools 12 are basically analogous to those used in machining equipment, though in the present instance the purpose of the tool is not that of obtaining a shape from a raw piece of metal. With reference to figures 6A to 6F, several variants of cutting stations with different tools are depicted. According to a first variant (figure 6A) the cutting tools 12 are mounted on toolholder bars 14 arranged radially projecting from the cylindrical surface of a shaft 15. Each bar 14 is arranged on a helical line traced on the surface of the shaft 15 according to one or more starts. Thus, the cutting tools 12 are suitably staggered. A second variant (figure 6B) envisages the overlapping of milling disks 24 to cutting tools 12 piece-formed in the disk 24. The overlapping is such as to attain a helical pattern of the cutting tools 12 on the cylindrical surface that is obtained. A third variant (figure 6C) envisages cutting tools 12 directly embedded in recesses 34 obtained in the body of the shaft 15, according to a helical pattern similar to the ones described above. The shaft 15a is made of a cylindrical vertical-axis bell, set in rotation by the ratio motor 16, to which there are secured the cutting tools 12. On the cylindrical side surface thereof there are obtained said recesses 34 for the tools 12, and, thereat, windows 35 for inletting the shaving T are provided. With the rotation of the bell, the tools 12 cut the shaving T, inviting it in the windows 35 and the shaving T falls in the bell. A fourth and a fifth variant envisage single or twin-cutting tools 12 at the rotating shaft connected to the ratio motor 16. Therefore, the single tools 12 (figure 6D) are coupled therebetween with the edge in the sense of rotation. The tools 12 are stacked, with the cutting blades suitably staggered, and secured to a vertical-axis support disk, to be secured to the shaft of the ratio motor 16. Therefore, the stack of tools will form a bottomless hollow cylinder 15b, with sharp projections. The tools 12 are assembled so as to leave free, at any level, openings at the sharp ends; this allows the cut shaving T to enter and fall in the array of tools 12. In the last variant (figure 6E), the tools are double-edged. Therefore, the individual tools 12 are coupled therebetween, with the blades oriented rotation-wise. The tools 12 are stacked, with the edges suitably staggered, and secured to a vertical-axis support disk to be secured to the ratio motor shaft. Therefore, the stack of tools 12 will form a bottomless hollow cylinder 15c, with sharp projections. The tools 12 are assembled so as to leave free, at any level, openings at the sharp ends; this allows the cut shaving T to enter and fall in the array of tools 12. In the latter three variants, the hollow shafts 15a, 15b and 15c act as means for collecting the shavings T. To the above described lead feeder device a person skilled in the art, in order to satisfy contingent needs, may effect variants, falling however in the protective scope intended for the present invention, as defined by the appended claims.

Claims

CLAIMS 1. A lead feeder device (1) for the production of lead oxide, comprising: * a line (2) for feeding lead in ingots (L); * one or more cutting tools (12) scraping the surface of an ingot (L) so as to produce shavings (T) curved according to a basically helical turn; and * means (18; 15a; 15b; 15c) for collecting said shavings and directing (30) the feeding of abrasion mills. 2. The device (1) according to claim 1 , wherein the feeding line (2) comprises a section (7) carrying individually the ingots (L). 3. The device (1) according to claim 1 , wherein the feeding line (2) comprises a section (9) that than receives the ingots arranged lengthwise. 4. The device (1) according to claim 1 or 3, wherein the feeding line (2) comprises means (9) for pushing the ingot (L) in the direction of a cutting station (10) containing said one or more tools (12). 5. The device (1) according to claim 4, wherein the pushing means (9) comprises a linear actuator (11) acting on a distal end of the ingot (L) with respect to the cutting station (10). 6. The device (1) according to any one of the preceding claims, wherein the cutting tools (12) are rotated about an axis perpendicular with respect to the direction of feed of the ingot (L). 7. The device (1) according to claim 6, wherein said axis is vertically arranged. 8. The device (1) according to any one of the preceding claims, wherein the cutting tools (12) are connected to a shaft (15) driven in rotation by a ratio motor (16) mechanically connected to a motor (17) of adequate power. 9. The device (1) according to any one of the preceding claims, wherein the cutting tools (12) are connected to a shaft (15) and their distribution on the shaft 15 is such that the cutting tools (12) cut on all the infed end of the ingot (L). 10. The device (1) according to any one of the preceding claims, wherein a cutting station (10), containing said one or more tools (12), comprises means for lubricating and cooling that uses water. 11. The device (1) according to any one of the preceding claims, wherein the cutting tools (12) are mounted on toolholder bars (14) arranged radially projecting from the cylindrical surface of a shaft (15), each bar (14) being arranged on a helical line traced on the surface of the shaft (15) according to one or more starts, so that the cutting tools (12) be staggered. 12. The device (1) according to any one of the claims 1 to 10, envisaging the overlapping of milling disks (24) to cutting tools (12), the overlapping being such as to attain a helical pattern of the cutting tools (12) on the cylindrical surface that is obtained. 13. The device (1) according to any one of the claims 1 to 10, wherein the cutting tools (12) are directly embedded in recesses (34) obtained in the body of the shaft (15) according to a helical pattern. 14. The device (1) according to claim 13, wherein the shaft (15) is made of a cylindrical bell to which there are secured the cutting tools (12), on the cylindrical side surface thereof there being obtained windows (35) for inletting the shaving (T) with the rotation of the bell (15a; 15b; 15c).