JP7259538B2 - liquid filter - Google Patents

Description

The present invention relates to liquid filters. Specifically, the present invention is a closed-type liquid filter typified by a continuous liquid filter used in nickel smelting using HPAL (high pressure sulfuric acid leaching) technology, etc., in which the treated liquid is prevented from entering the exhaust duct. It is a technique that prevents more reliably and imparts a high degree of safety to the liquid filter.

For example, in a hydrometallurgical process based on high pressure sulfuric acid leaching (HPAL) for recovering nickel from low-grade nickel oxide ore, conventionally, the gas in the gas phase is placed in a closed processing tank. A type of liquid filter provided with an exhaust mechanism for discharging to the outside of the liquid filter is widely used.

In a liquid filter having such a basic structure, the liquid level of the processing liquid in the processing tank is normally detected and fed back to the control mechanism to perform a sequence of operations such as supply and discharge of the processing liquid. controlled. However, in the liquid filter having the structure described above, in the unlikely event that a problem such as a malfunction of an instrument that detects the liquid level occurs, the processing liquid will enter the inside of the exhaust mechanism, and the continuation of the operation will be interrupted. Otherwise, there is a risk that the function of the exhaust system as an environmental smoke collection facility will be impaired, causing a serious situation in which harmful gas leaks out of the factory.

In order to prevent the above-mentioned risks from becoming apparent, a waste liquid transfer device (see Patent Document 1) having a mechanism for detecting abnormal inflow of waste liquid and stopping the operation of the pump as necessary, an upper liquid level detection unit and a lower A filtration tank (see Patent Document 2) or the like is used, which has a liquid level detection unit and controls fluctuations in the level of filtered water to be as small as possible.

JP-A-63-214388 JP-A-2005-58970

However, none of the conventional control methods for the processing liquid necessarily have sufficient safety measures against malfunction of the detector or the like. In a liquid filter such as a "continuous liquid filter", it is possible to more reliably prevent the infiltration of the processing liquid into the exhaust mechanism even if the device that detects the liquid level malfunctions. A technical means was required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid filter that can more reliably prevent the processing liquid from entering the inside of the exhaust mechanism even when a device that detects the liquid level malfunctions. do.

In a liquid filter such as a continuous liquid filter, the present inventors have found that the liquid level detection mechanism for detecting the upper limit of the liquid level is two types of upper limit detection devices, primary and secondary, each having a different function as described below. The inventors have found that the risk of the processing liquid entering the inside of the exhaust mechanism can be remarkably reduced by constructing the exhaust mechanism as described above, and have completed the present invention. Specifically, the present invention provides the following.

(1) A liquid filter comprising a closed processing tank, a processing liquid supply mechanism, a filtrate discharge mechanism, and an exhaust mechanism, wherein the liquid level of the processing liquid inside the processing tank is detected. A detection mechanism and a control mechanism for controlling the operations of the filtrate discharge mechanism and the exhaust mechanism, wherein the liquid level detection mechanism detects a full liquid state, which is a state in which the liquid level reaches a prescribed upper limit. and a secondary liquid level detection device capable of detecting a semi-full liquid state in which the liquid level reaches a sub-upper limit lower than the upper limit, The liquid level detection mechanism detects a preset reference time after the primary liquid level detection device detects the liquid full state or after the secondary liquid level detection device detects the semi-full liquid state. an attention signal emitting means for emitting an attention signal to the control mechanism at any time elapsed, the control mechanism, when receiving the attention signal, forcing the treatment liquid into the exhaust mechanism; A liquid filter having a control means for causing each mechanism of the liquid filter to perform a treatment liquid leakage prevention operation for preventing the infiltration of the liquid filter.

(2) The liquid filter according to (1), wherein the processing liquid leakage prevention operation includes an operation of opening the filtrate discharge mechanism to promote discharge of the filtrate from the processing tank.

(3) The processing liquid leakage prevention operation according to (1) or (2), wherein the processing liquid leakage prevention operation includes an operation of closing the exhaust mechanism to prevent the processing liquid from entering the interior of the exhaust mechanism from the processing bath. liquid filter.

(4) The liquid filter according to any one of (1) to (3), further comprising a device for detecting intrusion of liquid into the exhaust mechanism.

ADVANTAGE OF THE INVENTION According to the present invention, it is possible to provide a liquid filter that can more reliably prevent the processing liquid from entering the inside of the exhaust mechanism even when a device that detects the liquid level malfunctions. can.

BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional schematic diagram which shows typically a structure of the liquid filter of this invention. 4 is a flow chart showing the flow of the processing liquid leakage prevention operation in the liquid filter of the present invention.

Embodiments of the present invention will be described below. However, the present invention is not limited to the following embodiments.

<Liquid filter>
The liquid filter 10 of the present invention includes a processing tank 1, a processing liquid supply mechanism 3 for supplying a processing liquid to the inside of the processing tank 1, and a post-filtration treatment outside the processing tank 1, as in a conventional closed type processing tank. A filtrate discharge mechanism 4 for discharging a liquid (filtrate) and an exhaust mechanism 5 for discharging gas from the gas phase above the treatment liquid to the outside of the treatment tank are provided.

In addition to the basic configuration of the liquid filter, the liquid filter 10 of the present invention further includes a liquid level detection mechanism 2 having a unique configuration of the present invention, and a warning signal transmitted from the liquid level detection mechanism 2. Accordingly, a control mechanism 6 (not shown in FIG. 1, see FIG. 2) for controlling the operation of each mechanism provided in the liquid filter 10 is provided. Details such as the function of each mechanism will be described later.

[Treatment tank]
The liquid filter 10 has a closed processing tank 1 which operates in a state in which the gas phase portion is formed on the liquid surface of the liquid phase portion except when the processing liquid is filled. A filtration membrane (filter cloth) 11 is installed inside the treatment tank 1, and the treatment liquid (which usually contains impurities as solids; the same shall apply hereinafter) is continuously filtered through the filtration membrane 11. A filtrate from which impurities have been removed from the treated liquid can be obtained by filtering the treated liquid.

[Liquid level detection mechanism]
The liquid filter 10 has a liquid level detection mechanism 2 having a structure unique to the present invention. This liquid level detection mechanism 2 is a mechanism for detecting the liquid level of the processing liquid inside the processing tank 1. By combining two detection devices which detect the liquid levels independently defined at different heights, It is configured.

The main liquid level detection device 21, which is one device constituting the liquid level detection mechanism 2, is in a "full liquid state", which is a state in which the liquid level of the processing liquid inside the processing tank 1 reaches a specified "upper limit". It is a device that detects that Here, the "full liquid state" usually means a state in which the processing liquid is filled up to the top of the processing bath 1, but the "upper limit" of the liquid level that determines the "full liquid state" varies The liquid level may be arbitrarily set according to the structure, function, or operating conditions of each liquid filter. As shown in FIG. 1, the main liquid level detection device 21 is installed at a position where it can detect that the liquid level of the processing liquid has reached the "upper limit" and that it is in a "filled state".

A secondary liquid level detection device 22, which is another device that constitutes the liquid level detection mechanism 2, detects that the liquid level in the processing tank 1 is in a predetermined "semi-full liquid state". The term "semi-full liquid state" as used herein means that the inside of the processing tank 1 is at a predetermined "semi-upper limit" that is lower than the above-mentioned "upper limit" that defines the above-mentioned "full liquid state". It means that the liquid level of the processing liquid has reached. The "semi-upper limit" that defines the "semi-full liquid state" can be arbitrarily set according to the structure, function, or operating conditions of each individual liquid filter. As shown in FIG. 1, the secondary liquid level detection device 22 is installed at a position where it can detect the "semi-full liquid state" that has reached the "semi-upper limit".

Of the above two detection devices, the secondary liquid level detection device 22, in addition to the function of detecting the "semi-full liquid state", starts time measurement starting from the time when the "semi-full liquid state" is reached. It has a time measuring means 221 such as various timers capable of measuring the elapse of a preset "reference time" from the time when the "semi-full liquid state" is reached.

The liquid level detection mechanism 2 is set in advance when the main liquid level detection device 21 detects the "full liquid state" and after the secondary liquid level detection device 22 detects the "semi-full liquid state". It has caution signal transmitting means for transmitting a "caution signal" to the control mechanism 6 both when the "reference time" of (1) has elapsed and when the "reference time" has elapsed. Details of the flow of the operation for preventing leakage of the processing liquid to the exhaust mechanism 5 in which the operation of the liquid level detection mechanism 2 and the operation of the control mechanism 6 are interlocked will be described later.

It is preferable that the liquid filter 10 further include a lower limit detection device 23 capable of detecting that the liquid level has reached the lower limit.

It should be noted that each of the detection devices (21 to 23) described above can specifically be configured by appropriately using various conventionally known liquid level detection devices such as a vibrating level switch.

[Processing liquid supply mechanism]
In the liquid filter 10, the processing liquid supply mechanism 3 for supplying the processing liquid into the processing tank 1 may have the same structure as that of the conventional liquid filter. The treatment liquid supply mechanism 3 includes, for example, a water inlet valve 31, a treatment liquid inlet valve 32, etc. for starting or stopping the supply of treated water or treatment liquid.

[Filtrate discharge mechanism]
In the liquid filter 10, the filtrate discharge mechanism 4 for discharging the filtrate to the outside of the treatment tank 1 may have the same structure as a conventional liquid filter. The filtrate discharge mechanism 4 includes, for example, a filtrate outlet valve 41 for starting or stopping discharge of treated water or filtrate.

[Exhaust mechanism]
In the liquid filter 10, the exhaust mechanism 5 for discharging gas from the gas phase portion of the treatment tank 1 to the outside of the treatment tank 1 includes an exhaust gas duct 51, an exhaust gas outlet valve 52, and the like. For example, in the continuous liquid filter used in the wet process of the above-mentioned nickel refining process, etc., the gas in the gas phase of the processing tank 1 is exhausted through the exhaust mechanism 5, and the processing liquid is discharged inside the processing tank 1. be filled. Moreover, in many cases, this exhaust mechanism 5 functions in conjunction with environmental smoke collection equipment for the entire plant.

Further, it is preferable that the exhaust mechanism 5 is provided with a liquid infiltration detection device 53 for detecting infiltration of the processing liquid into the duct, for example, near the entrance of the exhaust gas duct 51 on the side of the processing tank 1 . As the liquid intrusion detection device 53, conventionally well-known various detection devices can be used, but a capacitance type or optical type wetness sensor or the like can be preferably used. It can also detect liquids that

[Control mechanism]
The control mechanism 6 prevents the treatment liquid from entering the inside of the exhaust mechanism 5 in response to a "caution signal" received from the liquid level detection mechanism 2 composed of the main liquid level detection device 21 and the secondary liquid level detection device 22. It has control means for causing each mechanism of the liquid filter 10 to perform a "treatment liquid leakage prevention operation" for preventing the leakage. The control mechanism 6 may be any mechanism that can exhibit the function of controlling the operations of the processing liquid supply mechanism 3, the filtrate discharge mechanism 4, and the exhaust mechanism 5 in response to the "caution signal". The specific form of the control mechanism 6 is not particularly limited, but in an electronic control device such as a programmable logic controller (PLC) used to control the operation sequence of each mechanism in a general liquid filter, the present invention The control mechanism 6 can be configured by operating a program programmed in accordance with the unique "liquid filter control method".

[Other mechanisms]
In addition, the liquid filter 10 is provided with a spray water inlet valve 71, a nitrogen inlet valve 72, a backwash liquid inlet valve 73, a drain valve 74, and the like, as required. For example, in the case of the above-mentioned continuous liquid filter, the filtered solid matter adhering to the filtration membrane 11 is supplied by the spray water inlet valve 71, the nitrogen inlet valve 72, and the backwash liquid inlet valve 73 and/or or flushed with nitrogen and discharged through drain valve 74;

The liquid filter of the present invention described above is implemented as a continuous liquid filter used in the nickel recovery process by the above-described high pressure sulfuric acid leaching (HPAL: abbreviation for High Pressure Acid Leach) as a representative example of a preferred embodiment. can be mentioned. However, the present invention is not limited to this, but includes a liquid filter in general having a sealed processing tank holding a liquid phase portion and a gas phase portion, and having a mechanism for discharging gas from the gas phase portion as necessary. can be widely applied to

<Method for controlling liquid filter>
In the liquid filter 10 having the structure described above, a control method capable of avoiding the infiltration of the processing liquid into the inside of the exhaust mechanism 5 even when a malfunction occurs in a device for detecting the liquid level is shown in FIG. 2 for explanation.

During normal operation of the liquid filter 10 , when the main liquid level detector 21 detects a “full liquid state”, a “caution signal S ₁ ” is sent to the control mechanism 6 . The control mechanism 6 receives the caution signal _S3 through the logical sum circuit (OR circuit), and issues a command to the filtrate discharge mechanism 4 to open the filtrate outlet valve 41 and start discharging the filtrate. , 52 to stop gas discharge. In this state, the processing liquid is continuously supplied into the processing tank 1 by the processing liquid supply mechanism 3, whereby the filtration process is started and the filtrate is obtained through the filtrate outlet valve 41. FIG. As long as the main liquid level detection device 21 is operating normally, the processing liquid is prevented from entering the inside of the exhaust mechanism 5 by the above commands. In other words, in this case, the normal operation of the filtrate discharge mechanism 4 and the exhaust mechanism 5 performed by the command from the control mechanism 6 is the "treatment liquid leakage prevention operation".

On the other hand, in the liquid filter 10, when the secondary liquid level detection device 22 detects the "semi-full liquid state", the "caution signal _S2 " is generated first, and the duration of the "caution signal _S2 " is measured by the time measuring means. Measure at 221. When the "semi-full state" ceases, the "caution signal _S2 " disappears and its duration returns to zero. On the other hand, if the "semi-full liquid state" continues and the "caution signal _S2 " is maintained, the "caution signal _S2 '" is sent to the control mechanism 6 when the above-described "reference time" has elapsed. be done. Also in this case, the control mechanism 6 that has received the caution signal _S3 through the logical sum circuit (OR circuit) sends the same command to the filtrate discharge mechanism 4 and the exhaust mechanism 5 as described above. Therefore, even when the main liquid level detection device 21 is not operating normally, the "treatment liquid leakage prevention operation" is activated by the command from the control mechanism 6. FIG. In this way, by measuring the duration of the "caution signal _S2 " by the time measuring means 221, it is possible to avoid inappropriate operation of the control mechanism 6 when the liquid in the treatment bath 1 tends to decrease. , the device can be simply constructed without requiring a device for knowing the rate of increase and decrease of the liquid level.

It should be noted that the "treatment liquid leakage prevention operation" in this specification is not limited to specific operations related to the filtrate discharge mechanism 4 and the exhaust mechanism 5 described above. This is done in accordance with the caution signal sent from the main liquid level detector 21 immediately after the detection of the "full liquid state" and the caution signal sent from the secondary liquid level detector 22 after the elapse of the reference time after the detection of the "semi-full liquid state". Any operation that can actually prevent the processing liquid from entering the inside of the exhaust mechanism 5 can be performed. included in the scope.

Further, as described above, when the liquid infiltration detection device 53 is installed in the exhaust mechanism 5 of the liquid filter 10, the "caution signal S ₄ (not shown)" to activate the "treatment liquid leakage prevention operation". However, in this case, an interlock is installed to issue an alarm in response to the transmission of the "caution signal _S4 " and to immediately stop the supply of the treatment liquid. Safety can be further improved. Further, depending on the degree of infiltration of the processing liquid, the drain valve 74 may be opened, or other equipment connected to the environmental smoke elimination facility may be used to prevent the infiltration of the processing liquid.

REFERENCE SIGNS LIST 1 treatment tank 11 filtration membrane 2 liquid level detection mechanism 21 primary liquid level detector 22 secondary liquid level detector 221 time measuring means 23 lower limit detector 3 treated liquid supply mechanism 31 water inlet valve 32 treated liquid inlet valve 4 filtrate discharge mechanism 41 Filtrate outlet valve 5 Exhaust mechanism 51 Exhaust gas duct 52 Gas outlet valve 53 Liquid intrusion detector 6 Control mechanism 71 Spray water inlet valve 72 Nitrogen inlet valve 73 Reverse cleaning liquid inlet valve 74 Drain valve 10 Liquid filter

Claims (4)

A liquid filter comprising a closed processing tank, a processing liquid supply mechanism, a filtrate discharge mechanism, and an exhaust mechanism,
a liquid level detection mechanism for detecting the liquid level of the processing liquid inside the processing tank;
a control mechanism for controlling the operation of the filtrate discharge mechanism and the exhaust mechanism;
The liquid level detection mechanism includes a main liquid level detection device capable of detecting a full liquid state in which the liquid level reaches a specified upper limit, and a semi-upper limit in which the liquid level reaches a position lower than the upper limit. and a secondary liquid level detection device capable of detecting a semi-full liquid state,
The liquid level detection mechanism detects when the main liquid level detection device detects the full liquid state, or when the secondary liquid level detection device detects the semi-full liquid state and continues the semi-full liquid state. a warning signal transmitting means for transmitting a warning signal to the control mechanism whenever a preset reference time elapses ;
The control mechanism has a control means for causing each mechanism of the liquid filter to perform a processing liquid leakage prevention operation for preventing the processing liquid from entering the inside of the exhaust mechanism when the caution signal is received.
liquid filter. 2. The liquid filter according to claim 1, wherein said processing liquid leakage prevention operation includes an operation of opening said filtrate discharge mechanism to promote discharge of filtrate from the processing tank. 3. The liquid filter according to claim 1, wherein the processing liquid leakage prevention operation includes an operation of closing the exhaust mechanism to prevent the processing liquid from entering the interior of the exhaust mechanism from the processing bath. 4. The liquid filter according to any one of claims 1 to 3, further comprising a device for detecting intrusion of liquid into said exhaust mechanism.

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