MXPA99010963A - Apparatus for and process of water granulating matte or slag - Google Patents

Abstract

Se describe una mata o escoria fundida que es granulada con agua alimentando la mata o escoria fundida a través de un lavador (10a, 10b) hacia un tanque granulador (11a, 11b). El tanque (11a, 11b) comprende paredes en declive y estáequipado con vertederos de sobrepujo ajustables (22b) y una o más boquillas de aspersión (19a, 19b). Las boquillas (19a, l9b) están colocadas de manera que el agua que emiten impacta sustancialmente en toda la mata o escoria fundida que es alimentada al tanque granulador (11a, 11b). El tanque de granulación (11a, 11b) opcionalmente estárevestido con un material polimérico para reducir el potencial de explosiones freáticas. El granulador estáopcionalmente equipado con un tubo de descarga de gas (16b), el cual puede ser conectado directamente a una torre de extinción (14b), la cual a su vez puede estar conectada a un sistema de ventilación inducida (15). El granulador preferiblemente estáequipado con una abertura de alivio de explosión (27b) que consiste de canales durables (28b), la abertura de alivio de explosión (27b) preferiblemente cubierta con un material polimérico (29b).

Description

APPARATUS FOR AND PROCESS OF GRANULATION WITH WATER OF MATA OR ESCORIA BACKGROUND OF THE INVENTION This invention relates to granulation with water. In one aspect, this invention relates to an apparatus useful for the granulation with water of molten slag or slag, while in another aspect, this invention relates to a slag or granulation method with water granulation. In still another aspect, this invention relates to an apparatus and method of slag or granulation with water in an environmentally safe manner and with a minimum, if any, of phreatic explosions. In the various pyrometallurgical processes, particularly non-ferrous processes, molten matte and slag are generated as an intermediate and by-product, respectively. The efficient handling of these materials favors their reduction to a fluid particle e. Many methods for making this reduction are known, and these include granulation with water, air granulation, milling, rotary atomization (as described in USP 5,409,521, which is incorporated herein by reference) and the like. For reasons of convenience, safety and cost, granulation with water is usually a preferred method of reducing the size of the mat and slag. A representative method of granulation with water is described in USP 5,468,279, which is incorporated herein by reference. Although all of the above techniques are effective to one degree or another, all are subject to improvement, particularly with respect to environmental and safety considerations. With regard to granulation with water in particular, improvements in the capture of gas emission and reduction in groundwater explosions are the objectives of a cont request.

COMPENDIUM OF THE INVENTION In accordance with this invention, the molten slag is slaked with water by feeding the molten slag through a scrubber to a granulator tank. The tank comprises sloping walls, and is equipped with one or more deflectors, which divide it into an active granulation zone and a sedimentation zone at rest. The tank is also equipped with adjule overflow weirs and a multitude of spray nozzles. These nozzles are positioned in such a way that the outgoing water collides on all or subtially all of the molten slag or slag that is fed to the granulator tank. The granulation tank is optionally coated with a polymeric material to reduce the potential for phreatic explosions. The granulator is also optionally equipped with a gas discharge pipe, which can be connected directly to an extinguishing tower, which in turn can be connected to an induced ventilation system. The granulator tank is also equipped with a bucket elevator to remove the granulated material. The overflow of water from the granulator is transferred to a thickener / clarifier to recover the solids. The granulation water recovered from the thickener / clarifier is cooled and recirculated, and the pH of this water is controlled to maximize the efficiency of removing the contaminants from the ventilation gas of the granulator.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic flow diagram of one mode of a granulation processes of mat scrubber matting towards two granulators towards a pelletized conveyor belt. Figure 2 is a schematic representation of the two granulators of Figure 1. Figure 3 is a schematic representation of the bucket excavator of Figures 1 and 2.

DESCRIPTION OF THE PREFERRED MODALITY The water-granulating apparatus of this invention is capable of granulating either molten slag or slag or a combination thereof. Typical slag and slag compositions include those generated in copper smelting processes such as those described in USP 5,449,395; 4,416,690; 5,217,427; and 5,007,959, all are incorporated herein by reference. Representative clumps and slags generated from nickel smelting processes are described in USP 5, 215,571, which is incorporated herein by reference. Similar numbers are used to designate similar parts through the drawings. Various items of equipment, such as valves, fittings, heaters and the like are omitted in order to simplify the description of the invention, but those skilled in the art will recognize that such conventional equipment can be, and is, employed as desired. A typical embodiment of the process of this invention is illustrated in Figure 1. The molten mat (for example, copper or nickel) or slag, in this case kills, is transported by scrubbers 10a and 10b from one of the melters or other kilns. p rometalurgics (not shown) towards the granulation tanks 11a and 11b. The molten matte is put in contact with the water inside these tanks, and is converted to granulated matte, which is collected at the bottom of the tanks. The bucket excavators 12a and 12b remove the pellet in a continuous or intermittent base from the bottom of the granulation tanks to the conveyor 13 or similar transport equipment, which transports the pellet to a storage or shipping facility or to another station for additional processing (none of which is shown in the Figures). Figure 2 illustrates one embodiment of the granulator of this invention. Typically, the granulator (here described in terms of the granulator 11b) includes an enclosed and ventilated tower 14b connected to a ventilation duct 15. The tower 14b is attached to the vapor cover 16b, which covers the granulation zone 17b. The granulation zone is equipped with an intermediate cauldron (for example, the boiler 18a shown in the section cut from the granulation zone 17a) positioned relative to one or more water nozzles (e.g., 19a and 19b) so that the molten mat discharged from the intermediate cauldron (which was received from the scrubber 10a or 10b, respectively) is immediately and completely in contact with the water discharged from the nozzles. The contact of the melted mat with the water generates steam, which is captured by the steam cover and ventilated through the tower to the ventilation duct. Typically and preferably, the intermediate boiler is located above the nozzle, and the nozzle is operated in such a manner as to eject a spray or cascade of water. The molten mat discharged from the cauldron in this way passes or falls through the sprinkling or cascade of water. After contacting the water, the molten mat is granulated and collected at the bottom of the granulation tank, that is, in the sedimentation zone 20b. The granulation zone 17b is separated from the settling zone 20b through a baffle 21b, which is typically one or more concrete or steel structures extending from the inner walls of the granulation tank. The settling zone 20b is also equipped with a granulation water overflow weir 22b, which will capture and divert the granulation water from the settling zone. The granulated mat is finally removed from the settling zone by digging buckets 23b, which are illustrated in greater detail in Figure 3. The granulation tank is also equipped with provisions (eg, an emergency washer 24b and an emergency container 25b) for controlling and directing any leakage of molten material that may occur away from the granulation area.

The granulator tank consists of reinforced concrete or other suitable construction material, for example, steel, and comprises sloping walls (as illustrated in Figure 3) to direct the granulated material towards the bucket elevator. Overflow weirs are located along the side of the tank to allow controlled removal of water, and preferably these dumps are adjustable. The landfills are isolated from the free board in the granulator and the turbulent water by metal divisions 26a and b, which extend into the water as shown in Figure 2. In one embodiment, the water enters the pit or tank through of a plate (not shown), typically made of stainless steel, which is equipped with a multitude of spray nozzles. The number, the diameter (size) and the placement of the nozzles can vary for convenience, the exact size, the number and placement of the nozzles as a function of the molten material, the parameters of the granulation operation, the final particle size desired of the granulated product and similar factors. The combination of all these factors finally determines the number and size of groundwater explosions. Optionally, the granulation pit is coated with a polymeric material, for example, a carbon tar epoxy, to reduce the potential for explosions of molten material. Although not wished to be bound by theory, it is believed that organic materials prevent metal-water explosions by interfering with the initiation of nucleate boiling at the abutting surface between the molten material and the granulation tank. The flow velocity of the water to the granulator tank will vary with the design of the tank, the nature and amount of molten material, the temperature of the water and other variables, but typically varies between approximately 30 and approximately 10 tons of water per ton of material , preferably between approximately 25 and 15 tons of water per ton of material. Depending on the various designs and operating variables of the granulation system with water, typical systems can routinely process 60 tons per hour (tph) of molten material, for example, copper matte, usually in excess of 85 tph , and some system designs and operations can process an excess of 200, even 300 tph of material with damaging explosions.

The water pressure is typically between about 4,569 and 8,436 kg / cm 2, preferably between about 5,975 and 7,381 kg / cm 2, to promote explosion-free granulation. Some small "detonations" with typical and useful to ensure that the operators of the system are operating normally. The water temperature is typically in an excess of 32.2 ° C, preferably between about 48.8 to 60 ° C.

Preferably, the granulators are equipped with an explosion relief opening 27b consisting of durable channels 28b, for example stainless steel, fixed in a gap to reduce the possibility of the solid material being expelled from the granulation area closest to the inlet washer of molten material. Here also, preferably the explosion relief opening is covered with a polymeric material 29b, for example, a polymer-coated fabric, and retained by elastic cords to prevent vapor release during normal operation, but allowing relief of pressurized gases in the case of an explosion (thus avoiding structural damage to the granulator tank and associated equipment). The granulator is preferably equipped with a gas discharge pipe, which is connected directly to an extinguishing tower (sweeper) 14b and then to an induced ventilation system (for example, ventilation duct 15). The quenching tower can be operated with a side stream of main granulation water to effect the sweeping of contaminants such as sulfur dioxide or particulate matter. The effluent from the extinguishing tower can flow directly into the granulation tank. Alternatively, the granulator can be ventilated through a distantly located sweeper (not shown). In another alternative, the granulator can be hermetically sealed to prevent any gas from escaping, with the exception of gases to the ventilated washer enclosure. The bucket elevator is used to remove material from the granulation tank, and is equipped with rollers, guides and a lift hoist, so that it is partially removed from the granulation tank for servicing or for controlled removal of material from the tank. This last procedure allows the tank to be "mined" if it is overloaded with granulated material. The overflow of water from the granulator is directed to a thickener / lightener (not shown) to recover any solids that have entered the granulation water. The lower flow of the thickener can optionally be fed to the slotted granulation excavator buckets to effect the filtration and recovery of the material. Alternatively, the lower flow can be directed to a filtration apparatus. The pH of the granulation water is controlled through the addition of a basic compound, such as NaOH, to keep the pH from approximately neutral to slightly basic. In one embodiment, water with controlled pH is used to sweep contaminants from the granulator ventilation gas. The granulation water can be cooled in a conventional cooling tower, and then recirculated to the granulation system. Preferably, a reserve water supply system is provided to ensure the flow of water to the granulation heads even in the event of a power failure that stops the main granulation pumps. Although this invention has been described in great detail with reference to the drawings and the various embodiments detailed above, this description is for the purpose of illustration and is not constructed as a limitation of the invention as described in the appended claims.

Claims (9)

1. CLAIMS 1. An apparatus for granulating molten material, the apparatus comprises: A. means for transporting a molten material from a source of molten material to a declining wall granulator tank having a free board area, the granulator tank is equipped with (i) water overflow weirs, landfills isolated from the free board area through at least one division extending to the granulator tank, (ii) a baffle to divide the granulator tank into a sedimentation zone and a granulation zone, (iii) means for reversing material leakage away from the granulation zone, and (iv) means for preventing the discharge of the solid material from the granulator tank to the transport means; B. means for projecting the water onto the molten material, as the molten material is discharged from the means for transporting to the granulation zone of the granulator tank, so that the molten material is converted to a granulated material and then collected in the sedimentation zone of the granulator tank; C. means for removing the granulated material from the sedimentation zone of the granulator tank; and D. means to capture gas emissions from the granulator tank.
2. 2. - A method for granulating a molten material, the method comprising the steps of: A. feeding a molten material into a granulation zone of a granulator tank; B. contact the molten material with sufficient water, the pH of the water is controlled from neutral to slightly basic, and in such a way in the granulation zone that the molten material is converted into a granulated material only with phreatic explosions that do not damage the granulator tank; C. collecting the granulated material in a sedimentation zone of the granulator tank; D. collect gas emissions from the granulator tank, and convert these emissions to a suitable form to discharge into the environment; E. recovering the water remaining from Step (B) of the granulator tank, converting the recovered water to a suitable form for use in Step (B), and recirculating the water recovered from Step (B); F. removing the granulated material from the sedimentation zone of the granulator tank with removably placed removal means; and G. diverting the leaks of the molten material away from the granulation zone of the granulator tank.
3. 3. The apparatus according to claim 1, further comprising means for recirculating the water projected from the granulation tank.
4. 4. The apparatus according to claim 1, further comprising means for controlling the pH of the projected water on a neutral to slightly basic scale.
5. 5. The apparatus according to claim 1, wherein the means for removing the granulated material comprises a bucket elevator, this elevator being tightly positioned relative to the bottom of the granulator tank.
6. 6. The apparatus according to claim 1, wherein the granulator tank is coated with a polymeric material.
7. 7. The apparatus according to claim 1, wherein the landfills are tightly placed in the granulator tank.
8. 8. The apparatus according to claim 3, wherein the recirculated water is passed through a thickener / clarifier to remove the suspended material.
9. 9. An apparatus for granulating molten material, the apparatus comprising: A. means for transporting a molten material from a source of molten material to a declining wall granulator tank having a free board area, the granulator tank equipped with (i) ) overflow water dumps, landfills isolated from the free board area through at least one division that extends into the granulator tank, landfills are tightly placed to control the height of the water in the granulator tank, (ii) a baffle for dividing the granulator tank into a settling zone and a granulation zone, (iii) a polymeric coating, (iv) means for diverting material leaks away from the granulation zone and (v) means for preventing discharge from the solid material of the granulator tank to the means of transportation; B. Means for projecting the pH of the water either neutral or slightly basic on the molten material, as the molten material is discharged from the conveying means towards the granulation zone of the granulator tank, so that the molten material is converted to a granulator material and then collected in the sedimentation zone of the granulator tank; a bucket elevator to remove the granulated material from the sedimentation zone of the granulator tank, the bucket elevator being tightly positioned relative to the bottom of the granulator tank; D. means to capture gas emissions from the granulator tank; and E. means for recirculating the water from the granulator tank back to the granulator tank.