FI124739B - Autoclave, procedure for emptying an autoclave and use of a connecting line - Google Patents

Description

An autoclave, a method for draining an autoclave and use of a

CONNECTION LINE FIELD OF THE INVENTION

The present invention relates to an autoclave, and more particularly to an autoclave according to the preamble of claim 1.

The present invention is also limited to a method for draining an autoclave, and more particularly to a method according to the preamble of claim 7.

The present invention is also concerned with the use of a connection line, and more particularly with the use of a claim 9.

BACKGROUND OF THE INVENTION

The invention relates to an autoclave for pressure leaching or oxidation of sulphide ores and concentrates. According to the invention, the autoclave has a combined water injection line and drain line. From now on in this application the water injection line for adding water or other liquid to the autoclave is referred to as a supply line and a drainage line for draining slurry from the autoclave is referred to as a drain line.

In a pressure leaching process, the chemical dissolution of soluble minerals within a solid ore or Concentrate is carried out at high temperatures and elevated pressures such that the solution containing metals is recovered. The pressure leaching process is carried out in autoclaves. The slurry in the air is heated and fed into the autoclave, where high-pressure steam, water or other liquid, chemicals and oxygen are applied to oxidize or leach the slurry in the air by a chemical reaction. Invariably when leaching valuable metals leached iron, aluminum or other species will precipitate within the autoclave. Whenever there are large amounts of Precipitation occurring there are invariably large amounts of scale also formed. Scale is almost always formed in the process and requirement to remove scale Mostly determines the length of time the autoclave is online. Another factor that affects operational time online is internal maintenance within the autoclave. Autoclaves will need to be shut down and be descaled and / or repaired and can be multiple times a year depending on scale formation rate and autoclave design.

It is commonly known that most autoclaves include drain nozzles installed into the bottom of the autoclave to allow for solution drainage and to allow scale removal. There are many problems with the use of drain nozzles.

One is that removal of the bottom drain nozzle flange cover is a major hazard. Manual unbolting of cover by personnel is hazardous because it is often not known to what extent drainage has occurred in autoclave and how much solution or slurry is above the nozzle. Another problem is that the drain nozzles become blocked with scale and slurry and become inoperable without physical intervention, i.e. the drain nozzle does not actually drain. A typical autoclave comprises a cylindrical chamber divided into different compartments, an inlet and an outlet for the media to enter and exit the autoclave and a waste piping connected to the lower part of the cylindrical chamber of the autoclave. Scale is removed from the autoclave through a nozzle to which the drain line is connected, i.e. a cluster nozzle, or through an agitator nozzle. First the autoclave is drained and then the scale is removed either manually lifted out through the agitator nozzle in the upper part of the autoclave or if the bottom cluster is installed the scale can be removed through the bottom nozzle but since the scale is formed inside the autoclave also on top of the nozzle it is difficult to open and then remove the scale. US 5535992A discloses an autoclave configuration for pressure leaching lateral ores at elevated temperatures. The autoclave configuration includes at least one primary autoclave. The primary autoclave includes a slurry inlet port for receiving slurries of lateritic air, an acid inlet port for receiving leaching acids, an agitation means for agitating the slurries of lateritic air, and an outlet port for removing partially leached slurries of lateritic in the air. A multi-compartment autoclave follows the primary autoclave. The multi-compartment autoclave is divided into at least two Chambers connected in series. The Chambers contain means for agitating the partially leached slurries and divider walls for separating the Chambers. An Inlet port is connected to the first of the Chambers for a receipt of partially leached slurries. An outlet port is connected to the last of a series of chambers for removal of the finally leached slurries. A bypass conduit is connected to the lateritic slurry supply and the multi-compartment autoclave. The bypass conduit is for periodically isolating the primary autoclave for removal of scale while leaching lateritic air in the multi-compartment autoclave.

The autoclave has to be drained for cleaning and maintenance purposes and the problem with a typical autoclave is that there is a drain nozzle on the bottom of the autoclave which with time will be blocked with scale and unblocking the drain nozzle with undrained acidic slurry sitting above it is hazardous and time-consuming because of the blockage above the drain nozzle. One of the problems associated with the arrangement disclosed in US 5535992A is that it needs a separate bypass conduit which itself is an extra investment and requires additional space in the process.

BRIEF DESCRIPTION OF THE INVENTION

An object of the present invention is thus to provide an autoclave and a method for draining the autoclave so as to alleviate the above disadvantages. The objects of the invention are achieved by an autoclave and a method which is characterized by what is stated in the independent claims. The object of the invention is also achieved by the use of a connection line as stated in the independent claim. The preferred embodiments of the invention are disclosed in the dependent claims.

The invention is based on the idea of having a combined line for adding water to the autoclave and draining the autoclave. The invention is further based on the idea of having a supply line for adding water to the autoclave which is always online or regularly used and connecting it to the drain nozzle so that the drain nozzle remains without scale sitting above and that autoclave can be drained once shutdown. With this invention there is no uncertainty about how much potentially acidic liquid remains in the autoclave above the drain nozzle and the drain nozzle is not blocked and can be used without intervention or clearing a blocked nozzle.

This invention provides an improved drainage that helps reduce the risk associated with autoclave drainage by providing a positive drainage solution and slurry above the nozzle that will be removed during autoclave cleaning and maintenance. The drain nozzle will remain unobstructed because of the quench water being online during the operation of the autoclave and that way keeping the water pipeline always clear and when the autoclave is shutdown there will be a complete drainage of the autoclave.

The invention is based on the idea of having a common line for adding liquid to the autoclave and for draining the autoclave. The leaching of sulphide ores and concentrates require that quench water is added. The quench water is added through a supply line for adding liquid. By supplying the cooling liquid to the autoclave an Aperture comprising a drain nozzle in the bottom part of the autoclave remains open and without scale blocking it so that when the autoclave is drained the drainage occurs effectively and without any blockages. In other words, fluid communication between the autoclave and the connection line is arranged in the bottom part of the autoclave and liquid from the supply line through the connection line keeps the fluid communication open such that the fluid communication between the autoclave and the connection line is formed so that the drainage from the autoclave through the connection line and further through the drain line can be arranged effectively. The fluid communication between the autoclave and the connection line is formed through an Aperture in the bottom part of the autoclave. The Aperture preferably consists of a drain nozzle. So the autoclave further comprises a drain nozzle for draining the autoclave and said drain nozzle is arranged in the bottom part of the autoclave and said connection line is connected to the autoclave via the drain nozzle. The drain nozzle is preferably bidirectional so that the liquid can flow through the drain line from the connection line into the autoclave or that the autoclave can be drained through the drain nozzle into the connection line.

According to the invention, the autoclave for leaching and oxidizing ores comprises an inlet for receiving slurries from ore into the autoclave, agitation means for agitating slurries from ore in the autoclave, and an outlet for removing at least partially leached slurries from ore from the autoclave. The autoclave further comprises a supply line in the fluid communication with the autoclave for adding liquid to the autoclave, the drain line in the fluid communication with the autoclave for draining the autoclave, and the connection line connected to the autoclave and being in fluid communication. with the autoclave. The connection line is in fluid communication also with the supply line and with the drain line such that the supply line and the drain line are connected to the autoclave through the same connection line. The autoclave further comprises at least one valve such that the flow direction in the connection line is changeable either from the supply line via the connection line to the autoclave or from the autoclave via the connection line to the drain line. In this application, the term fluid communication means that there is a connection for a fluid flow to go from one location to another.

The autoclave comprises a supply line for adding liquid into the autoclave and a drain line for draining slurry from the autoclave and the connection line connected to the autoclave and being in fluid communication with the autoclave. The supply line and drain line have fluid communication with the connection line and with the autoclave through said connection line, the supply line and the drain line have a valve for closing and opening said line.

According to the method of the invention for draining an autoclave, the autoclave has sulphide ores and liquid or other fluid substance inside the autoclave and the autoclave comprises a supply line for adding liquid into the autoclave for quenching. The autoclave further comprises a drain line for draining slurry from the autoclave and the connection line connected to the autoclave and being in fluid communication with the autoclave. The supply line and drain line have fluid communication with the connection line and with the autoclave through said connection line, the supply line and the drain line have a valve for closing and opening said line. The method comprises the steps of closing the valve in the supply line for closing the fluid communication between the supply line and the connection line, opening the valve in the drain line for opening the fluid communication between the drain line and the connection line, and draining slurry or liquid or other fluid substance from the autoclave through the connection line and through the drain line out of the autoclave. In a preferred embodiment of the invention, the method further comprises a step of changing the flow direction in the connection line with a bidirectional valve in a drain nozzle arranged in the autoclave.

So according to the method of the invention an autoclave having slurry or liquid or other fluid substance inside the autoclave is drained in the following continent: closing the valve in the supply line for closing the fluid communication between the supply line and the connection line, opening the valve in the drain line for opening the fluid communication between the drain line and the connection line, changing the flow direction in the connection line with a bidirectional valve, and draining slurry or liquid or other fluid substance from the autoclave through the connection line and through the drain line out of the autoclave.

According to the use of the invention, the connection line in an autoclave is used for adding liquid into the autoclave and for draining slurry or liquid or other fluid substance out of the autoclave.

An advantage of this invention is that the separate nozzles are not required for the liquid supply and for the drainage of the slurry so the number of nozzles in the autoclave can be minimized which burdens the autoclave significantly. Another advantage of the invention is that the risks with maintenance are minimized when considering opening the drain nozzle because the slurry sitting above the drain nozzle is minimized when fluid communication keeps the area clear from the scale. Another advantage of the invention is that the operation time will be longer since the requirement for removing scale is smaller.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in greater detail by means of preferred embodiments with reference to the attached drawing, in which

Figure 1 shows an autoclave according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 shows an autoclave 1 for leaching sulphides and concentrates and ores, said autoclave 1 comprising an inlet 2 for receiving slurries from the air into the autoclave 1, agitation means 3 for agitating the slurries from the air into the autoclave 1 and an outlet 4 for removing the at least partially leached slurries of air from the autoclave 1. The autoclave 1 further comprises a supply line 5 in a fluid communication with the autoclave 1 for adding liquid to the autoclave 1. The autoclave 1 further comprises a drain line 6 in a fluid communication with the autoclave 1 for draining the autoclave 1 and the connection line 7 connected to the autoclave 1 and being in the fluid communication with the autoclave 1, the connection line 7 being in the fluid communication also with the supply line 5 and with the drain line 6 such that supply line 5 and drain line 6 are connected to the autoclave through connection line 7.

The autoclave 1 further comprises at least one valve 8, 9 such that the flow direction in the connection line 7 is changeable either from the supply line 5 to the autoclave 1 or from the autoclave 1 via the connection line 7 to the drain line 6.

The autoclave 1 that comprises the supply line 5 for adding liquid into the autoclave 1, the drain line 6 for draining slurry from the autoclave 1 and the connection line 7 connected to the autoclave 1 and being in a fluid communication with the autoclave 1, said supply line 5 and said drain line 6 having fluid communication with the autoclave 1 through the connection line 7, is used for leaching ores and is a part of the process for leaching ores, which is typically water, is added during the process . The liquid is added to the process such that the supply line 5 supplies the liquid and the connection line 7 further leads the liquid coming from the supply line 5 into the autoclave 1. From time to time the autoclave 1 has to be drained in which method for draining the autoclave 1 is used. The method comprises the steps of closing the valve 8 in the supply line 5 for closing the fluid communication between the supply line 5 and the connection line 7, opening the valve 9 in the drain line 6 for opening the fluid communication between the drain line 6 and connection line 7, changing flow direction in connection line 7 with a bidirectional valve 10, and draining slurry or liquid or other fluid substance from the autoclave 1 through the connection line 7 and through the drain line 6 out of the autoclave 1 .

In a preferred embodiment of the invention, the autoclave 1 comprises an Aperture forming fluid communication between the autoclave 1 and the Aperture is arranged in the bottom part of the autoclave 1. The material of the connection line 7 is preferably alloy steel. or some other corrosion resistant material.

The connection line 7 is used for adding liquid into autoclave 1 and for draining slurry or liquid or other fluid substance out of autoclave 1 so it directs fluid in both directions in connection line 7.

It will be obvious to a person skilled in the art that, as technology advances, the Inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.

Claims (9)

A pressure vessel (1) for dissolving and / or oxidizing sulfide ore and concentrate, said pressure vessel (1) comprising an inlet (2) for receiving ore slurry in a pressure vessel (1), mixing means (3) for mixing ore slurry in the pressure vessel (1) and outlet (4). ) for removing at least partially dissolved ore slurry from the pressure vessel (1), the pressure vessel (1) further comprises a feed line (5) in fluid communication with the pressure vessel (1) for cooling the pressure vessel (1), characterized in that the pressure vessel (1) (6), which is in fluid communication with the pressure vessel (1) for emptying the pressure vessel (1), and a connecting line (7) connected to the pressure vessel (1) and in fluid communication with the pressure vessel (1), ) and the drain line (6) so that the feed line (5) and the drain line (6) are inserted into the pressure vessel (1) via the connecting line (7). Pressure vessel (1) according to claim 1, characterized in that the flow connection between the pressure vessel (1) and the connecting line (7) is arranged in the bottom part of the pressure vessel (1). Pressure vessel (1) according to claim 1 or 2, characterized in that the pressure vessel further comprises an emptying nozzle for emptying the pressure vessel (1), said emptying nozzle being arranged at the lower part of the pressure vessel (1) and said connecting line (7) connected to the pressure vessel (1). Pressure container (1) according to claim 3, characterized in that the drain nozzle is bidirectional so that the liquid can flow through the drain nozzle from the connecting line (7) to the pressure tank (1) or the pressure tank (1) can be drained through the drain nozzle to the connecting line (7). Pressure vessel (1) according to one of Claims 1 to 4, characterized in that the pressure vessel (1) further comprises at least one valve (8, 9) such that the flow direction in the connecting line (7) can be changed either from the supply line (5) to the connecting line (7). through the pressure vessel (1) or from the pressure vessel (1) via the connecting line (7) to the discharge line (6). Pressure vessel (1) according to one of Claims 1 to 5, characterized in that the material of the connecting line (7) is made of alloy steel or some other corrosion-resistant material. A method for emptying a pressure vessel (1), wherein the pressure vessel (1) contains sulfide ore and liquid or other liquid substance, said pressure vessel (1) comprising a feed line (5) for adding liquid to the pressure vessel (1) for cooling, characterized in that ) further comprises an emptying line (6) for emptying sludge from the pressure vessel (1) and a connecting line (7) connected to the pressure vessel (1) and in fluid communication with the pressure vessel (1), said supply line (5) and said emptying line (6) 7) and with the pressure vessel (1) via said connecting line (7), the supply line (5) and the drain line (6) having a valve (8, 9) for closing and opening said line, the method comprising the steps of: closing the valve (8) 5) to close the flow connection between the feed line (5) and the connecting line (7), - open the valve (9) in the drain line (6) vi for opening a flow connection between the discharge line (6) and the connecting line (7), and - discharging the slurry or liquid or other liquid material from the pressure vessel (1) through the connecting line (7) and the discharge line (6) out of the pressure vessel (1). The method according to claim 7, characterized in that the method further comprises the step of reversing the flow direction in the connection line (7) by means of a two-way valve (10) in the discharge nozzle provided in the pressure vessel. Use of a connecting line (7) in a pressure vessel (1) according to claim 1 for adding liquid to the pressure vessel (1) and evacuating the slurry or liquid or liquid substance from the pressure vessel (1).