CN101839892B - Ore milling concentration monitoring method for wet ball mill - Google Patents

Abstract

The invention relates to an ore milling concentration monitoring method for a wet ball mill. The method comprises the following steps of: 1) arranging a vibration sensor and a data acquisition device on a cylindrical wall of the ball mill; 2) acquiring vibration signals of the cylindrical wall of the ball mill by the vibration sensor, transmitting the vibration signals to the a data acquisition device, and drawing a statistical histogram of the vibration signals by the data acquisition device; 3) adopting laplace distribution of zero mean as best fit approximation of vibration signal distribution of the cylindrical wall of the ball mill according to the statistical histogram, and obtaining an estimated value of a vibration signal statistical parameter according to a maximum likelihood estimation of the laplace distribution; 4) changing the ore milling concentration in the ball mill to obtain a corresponding parameter estimated value; 5) expressing the ore milling concentration Cw in the ball mill as undetermined parameters a0, a1 and a2 in a quadratic polynomial determination expression of the ore milling concentration estimated value; and 6) acquiring the vibration signals of the cylindrical wall under different conditions, calculating the estimated value of the statistical parameter, substituting the estimated value into a quadratic polynomial determined in the step 5), and obtaining the corresponding estimated value of the ore milling concentration through calculation.

Description

A kind of ore milling concentration monitoring method of ball mill by wet process

Technical field

The present invention relates to a kind of monitoring method, particularly about a kind of ore milling concentration monitoring method of ball mill by wet process.

Background technology

Bowl mill is an important milling equipment during mineral resources are produced, and its major function is that ore is ground into the needed granularity of subsequent production technology.Bowl mill is divided into two kinds of dry method ball mill and ball mill by wet process, whether needs to add water when the key distinction is ore grinding as middle break-in medium, and the discharge mode of ore in the bowl mill.Do not add water during dry method ball mill work, the ore that grinds is in time discharged bowl mill by air blast; Need add water during ball mill by wet process work, utilize the flowability and the interior angle of inclination of bowl mill that grind ore and the composite ore pulp of water, the ore that grinds is discharged bowl mill by sieve aperture.Therefore, according to the difference of subsequent production technological requirement, dry method ball mill is the common equipment of fuel-burning power plant coal powder process normally, and ball mill by wet process then is generally used for the ore dressing production of non-ferrous metal, as the grinding of non-ferrous metals such as copper, nickel, molybdenum, manganese, tungsten.

In process of production, monitor most important to the operating condition of bowl mill.If bowl mill moves under unusual service condition for a long time, not only will influence the quality of production of ore grinding link, also may cause " sky is pounded " and accidents such as " tripe rise ", thus damage equipment, even interrupt the production of whole mineral resources.

For dry method ball mill, the controlling level of bowl mill inside directly influence grinds the discharge of ore, thereby is the key parameter of operating condition monitoring.At present there has been certain methods can be used for detecting the material level of dry method ball mill inside both at home and abroad, for example detect the leeway of bowl mill feeding mouth and discharging opening, the motor power (output) that drives the grinding machine rotation and grinding machine operation noise etc., but these methods all have lower, the easy shortcoming such as affected by environment of sensitivity, so practical application effect is relatively poor.Patent " based on the material level detection method and the pick-up unit thereof of bowl mill rotary barrel vibration signal " (application number: 200710131415.2), change the influence of steel ball according to controlling level in the dry method ball mill at grinding machine internal motion track, proposed a kind of method that detects bowl mill barrel Point Of Maximal Impulse, thereby realized monitoring controlling level in the bowl mill.

For ball mill by wet process, water is the intermediate medium that grinds, and the efflux velocity of material depends on the concentration of inner ore and aqueous mixtures in the bowl mill, and promptly the percentage by weight of ore and water is called ore milling concentration.Ore milling concentration in the bowl mill is low more, and ore is short more in the residence time of bowl mill; Ore milling concentration is high more, and then the residence time of ore in bowl mill is long more.Because bowl mill is the continuous collision between steel ball, ore and the liner plate that relies in the cylinder ore particles is ground, so the ore milling concentration in the bowl mill will directly influence the granularity that bowl mill is discharged ore, the i.e. quality of production of grinding process.In addition, if the ore milling concentration in the bowl mill is in when higher for a long time, the ore efflux velocity is lower than the ore delivery rate of bowl mill porch, and material will increase in the bowl mill, even cause catastrophic failures such as " tripe rise ".Therefore, monitor most important to the ore milling concentration of ball mill by wet process inside.

Because the principle of work of ball mill by wet process and dry method ball mill has than big difference, the operating condition monitoring method of some dry method ball mills as power of motor method and operation noise method etc., can be applied to the monitoring of ball mill by wet process, but practical application effect is very poor at present.The other method as pressure differential method, then can't be used in the monitoring of ball mill by wet process operating condition.In addition, because ore pulp and steel ball hybrid motion in the ball mill by wet process, ore pulp does not influence the movement locus of steel ball basically, the position basic fixed of bowl mill barrel Point Of Maximal Impulse, the not influence that changes with ore pulp in the bowl mill what and ore milling concentration, therefore, be difficult to monitor ore milling concentration in the bowl mill by detecting bowl mill barrel Point Of Maximal Impulse.

Summary of the invention

At the problems referred to above, the purpose of this invention is to provide a kind of ore milling concentration monitoring method of ball mill by wet process, this method can be monitored the ore milling concentration of bowl mill inside quickly and accurately when bowl mill moves.

For achieving the above object, the present invention takes following technical scheme: a kind of ore milling concentration monitoring method of ball mill by wet process, it may further comprise the steps: 1) vibration transducer is installed on the barrel of bowl mill, and vibration transducer connects a data collector by cable; Preset central processing unit, analog digital converting unit and data storage cell in the data collector; 2) sample frequency that data collector is set is f, and the ore milling concentration in the bowl mill is C _w, gather the vibration signal of bowl mill barrel by vibration transducer, and send data collector to, draw the statistic histogram of vibration signal data by data collector; 3) according to step 2) statistic histogram drawn, the best fit approximation that adopts the laplacian distribution of zero-mean to distribute as bowl mill barrel vibration signal, promptly the probability density function p (x) of vibration signal is:

$p\left(x\right)=\frac{1}{2b}\exp (-\frac{\left|x\right|}{b})---\left(1\right)$

Wherein, b is the vibration signal statistical parameter, and x is the vibration signal of barrel, estimates according to the maximum likelihood of laplacian distribution, obtains the estimated value of vibration signal statistical parameter b

For:

$\hat{b}=\frac{1}{N}\underset{i=1}{\overset{N}{\mathrm{\Σ}}}\left|x\left(i\right)\right|---\left(2\right)$

Wherein, N is a barrel when rotating a circle, the counting of the vibration signal of data collector record; X (i), i=1,2 ..., N is a barrel when rotating a circle, the sampled value of the vibration signal that the steel-ball collision barrel in the cylindrical shell produces; 4) change the interior ore milling concentration C of bowl mill _w, and write down different ore milling concentration C _wDown, the vibration signal x (i) of barrel, i=1,2 ..., N calculates estimated value according to (2) formula

The record sample

Wherein, k=1,2 ..., l is the experiment group of ore milling concentration for a change, amounts to the experiment of l group; 5) get quadratic polynomial

${\hat{C}}_w=p\left(\hat{b}\right)=a_0+a_1\hat{b}+a_2{\hat{b}}^2---\left(3\right)$

Wherein,

Be the ore milling concentration C in the bowl mill _wEstimated value, by Calculate gained; a ₀, a ₁, a ₂Be undetermined parameter, try to achieve undetermined parameter a ₀, a ₁, a ₂, determine (3) formula; 6) gather the barrel vibration signal x (i) in the bowl mill operational process under the different situations, i=1,2 ..., N is by the estimated value of central processing unit according to (2) formula counting statistics parameter

Bring in (3) formula of determining in the step 5), calculate the estimated value of corresponding ore milling concentration

Described step 2) in, the method for drawing statistic histogram is: the sample frequency that 1. data collector is set is f, according to the rotational speed omega of bowl mill _r, when calculating barrel and rotate a circle by central processing unit, the points N of the vibration signal of data collector record; 2. the ore milling concentration that is provided with in the bowl mill is C _w, when central processing unit control analog digital converting unit collection bowl mill barrel rotates a circle, the vibration signal x (i) that the steel-ball collision barrel in the ball mill barrel that vibration transducer transmits produces, i=1,2 ..., N, and be stored in the data storage cell; 3. by central processing unit the vibration signal that collects is divided into groups, it is n that packet count is set; Central processing unit is according to the maximal value x of vibration signal _MaxMinimum value x with vibration signal _MinObtain the width Delta of group distance: the frequency of vibration signal appearance in each group when 4. adding up the bowl mill barrel and rotating a circle, the computing method of each class frequency are: with every group of vibration signal sampled value count divided by, when barrel rotates a circle, the points N of the vibration signal of data collector record; 5. be horizontal ordinate with the vibration signal data, each class frequency is an ordinate, draws the statistic histogram of barrel vibration signal.

Described step 1. in, the points N of the vibration signal of data collector record is:

$N=\mathrm{fix}\left(\frac{60f}{{\mathrm{\ω}}_r}\right)$

Wherein, fix () expression round numbers; Rotational speed omega _rUnit be rpm; The unit of sample frequency f is Hz.

Described step 3. in, the group that central processing unit is obtained apart from width Delta is:

$\mathrm{\Δ}=\frac{x_{\max }-x_{\min }}{n}$

Described step 4. in, the frequency that the 1st group of vibration signal occurs is x (i) ∈ [x _Min, x _MinCounting+Δ) divided by N; The frequency that n group vibration signal occurs is x (i) ∈ [x _Max-Δ, x _Max] in count divided by N.

In the described step 5), undetermined parameter a ₀, a ₁, a ₂Try to achieve, satisfy the estimated value of ore milling concentration in the bowl mill

With ore milling concentration C in the bowl mill _wDifference Q minimum, that is:

$Q=\underset{k=1}{\overset{l}{\mathrm{\Σ}}}{(C_w\left(k\right)-{\hat{C}}_w\left(k\right))}^2=\underset{k=1}{\overset{l}{\mathrm{\Σ}}}{(C_w\left(k\right)-p\left(\hat{b}\left(k\right)\right))}^2=\min$

The present invention is owing to take above technical scheme, it has the following advantages: 1, the present invention is owing to be equipped with vibration transducer and data collector on the barrel of bowl mill, therefore, barrel vibration signal in the time of can directly detecting the bowl mill rotating operation, detection limit can more direct reaction sphere grinding machine inside running status, detection sensitivity is higher, and has stronger antijamming capability, work is not subject to the environmental impact of production scene, has stronger practicality.2, the present invention is owing to the vibration signal data according to barrel, and each class frequency of vibration signal data, draw out statistic histogram, therefore, according to statistic histogram, when the laplacian distribution of employing zero-mean is moved as ball mill by wet process, the optimal estimation of barrel vibration signal statistical distribution, with the estimated value of the scale parameter characteristic quantity as the barrel vibration signal, this characteristic quantity has good stability, the characteristics that discrimination is big.3, the present invention only need do additive operation when bowl mill barrel vibration signal statistical characteristic value calculates, and has adopted the corresponding relation between the ore milling concentration in fitting of a polynomial barrel vibration signal statistical nature and the bowl mill, and calculated amount is little, realizes easily.4, the present invention only needs to be provided with vibration transducer and data collector on ball mill by wet process, can monitor the operating condition of bowl mill, and this type of bowl mill is except that using in the non-ferrous metal ore field, also be widely used in fields such as chemical industry, metallurgy, therefore, but detection method provided by the present invention has certain generalization.The present invention is skillfully constructed, and is accurate and practical, and the operational efficiency that can greatly improve institute's watch-dog is also effectively avoided the accident of equipment operation, therefore, can be widely used in the monitoring system in fields such as non-ferrous metal ore field, chemical industry and metallurgy.

Description of drawings

Fig. 1 is apparatus of the present invention synoptic diagram

Fig. 2 is a data collector module diagram of the present invention

Fig. 3 is that the bowl mill barrel rotates the vibration signal sampled point of one-period and the corresponding relation figure of sampled value in the embodiment of the invention

Fig. 4 is the statistic histogram that the bowl mill barrel rotates the vibration signal of one-period in the embodiment of the invention

Fig. 5 is the laplacian distribution figure that the bowl mill barrel rotates the vibration signal of one-period in the embodiment of the invention

Fig. 6 is that the interior ore milling concentration of bowl mill changes at 85% o'clock, barrel vibration signal statistical parameter estimated value from 0% in the embodiment of the invention

With ore milling concentration C _wCorresponding relation figure

Embodiment

Below in conjunction with drawings and Examples the present invention is described in detail.

The present invention is based on the time domain statistical study of ball mill by wet process (hereinafter to be referred as bowl mill) barrel vibration signal and monitors the interior ore milling concentration of bowl mill, and it may further comprise the steps:

1) as shown in Figure 1, the vibration transducer 2 and a data collector 3 of a detection vibration signal is installed on the barrel 1 of bowl mill, vibration transducer 2 connects data collectors 3 by cable 4.As shown in Figure 2, preset central processing unit 31 in the data collector 3, analog digital converting unit 32 and data storage cell 33.

2) sample frequency that data collector 3 is set is f.Rotational speed omega according to bowl mill _r, in the time of can being calculated barrel 1 and rotated a circle by central processing unit 31, the points N of the vibration signal of data collector 3 records be:

$N=\mathrm{fix}\left(\frac{60f}{{\mathrm{\ω}}_r}\right)---\left(1\right)$

Wherein, fix () expression round numbers; Rotational speed omega _rUnit be rpm; F is the sample frequency of data collector 3, and unit is Hz.

3) when bowl mill moves, the steel ball in the cylindrical shell constantly collides barrel 1 and produces vibration signal x, and the ore milling concentration that is provided with in the bowl mill is C _wVibration signal when the bowl mill barrel 1 that central processing unit 31 control analog digital converting unit 32 transmit vibration transducer 2 rotates a circle carries out digital conversion, and is stored in the data storage cell 33.

When 4) bowl mill barrel 1 rotated a circle, the vibration signal sampled value of storage was x (i) in the data storage cell 33, i=1, and 2 ..., N, by central processing unit 31, obtaining its maximal value is x _Max, minimum value is x _MinPacket count was n when statistics was set, and the width Delta of being obtained the group distance by central processing unit 31 is:

$\mathrm{\Δ}=\frac{x_{\max }-x_{\min }}{n}---\left(2\right)$

The frequency that vibration signal occurred in each group when statistics bowl mill barrel 1 rotated a circle is vibration signal sampled value x (i) ∈ [x the 1st group of frequency that occurs for example _Min, x _MinCounting divided by N+Δ), the frequency that occurs in the n group is x (i) ∈ [x _Max-Δ, x _Max] count divided by N.Vibration signal data with the barrel 1 gathered are horizontal ordinate, and each class frequency is the statistic histogram that ordinate is drawn barrel 1 vibration signal.

The statistic histogram of vibration signal when 5) rotating a circle according to bowl mill barrel 1 adopts the best fit approximation of the laplacian distribution of zero-mean as the distribution of bowl mill barrel 1 vibration signal, and promptly the probability density function p (x) of vibration signal is:

$p\left(x\right)=\frac{1}{2b}\exp (-\frac{\left|x\right|}{b})---\left(3\right)$

Maximum likelihood according to laplacian distribution is estimated, obtains the estimated value of statistical parameter b

For:

$\hat{b}=\frac{1}{N}\underset{i=1}{\overset{N}{\mathrm{\Σ}}}\left|x\left(i\right)\right|---\left(4\right)$

X (i) wherein, i=1,2 ..., N is the vibration signal sampled value, N is that the vibration signals collecting that bowl mill barrel 1 rotates a week is counted.

6) by increasing or reduce the water yield in the bowl mill, change ore milling concentration, and write down under the different ore milling concentrations, the vibration signal of barrel 1 is according to the estimated value of (4) formula counting statistics parameter b

The record sample

Wherein, k=1,2 ..., l is the experiment group of ore milling concentration for a change, amounts to the experiment of l group, C _w(k) be the corresponding interior ore milling concentration of bowl mill, Estimated value for the vibration signal statistical parameter of correspondence.

7) get quadratic polynomial

${\hat{C}}_w=p\left(\hat{b}\right)=a_0+a_1\hat{b}+a_2{\hat{b}}^2---\left(5\right)$

Wherein, Be the ore milling concentration C in the bowl mill _wEstimated value, by

Calculate gained, a ₀, a ₁, a ₂Should make the estimated value of ore milling concentration in the bowl mill

With ore milling concentration C in the bowl mill _wDifference Q minimum, that is:

$Q=\underset{k=1}{\overset{l}{\mathrm{\Σ}}}{(C_w\left(k\right)-{\hat{C}}_w\left(k\right))}^2=\underset{k=1}{\overset{l}{\mathrm{\Σ}}}{(C_w\left(k\right)-p\left(\hat{b}\left(k\right)\right))}^2=\min ---\left(6\right)$

A is tried to achieve in calculating according to formula (6) ₀, a ₁, a ₂Thereby, determine formula (5).

8) gather the barrel vibration signal x (i) in the bowl mill operational process under the different situations, i=1,2 ..., N is by the estimated value of central processing unit 31 according to (4) formula counting statistics parameter Bring in (5) formula of determining in the step 7), can obtain the estimated value of corresponding ore milling concentration

In the foregoing description, the group in the step 4) also can adopt other method apart from width Delta and group division, thereby draws out the statistic histogram of vibration signal data, belongs to prior art, no longer describes in detail at this.

Enumerate a specific embodiment below:

Select XMQL-Ф 420 * 450 ball mill by wet process among this embodiment, this drum's speed of rotation is ω _r=57rpm.Range is installed on the bowl mill barrel is ± 2500m/s ²Accelerometer as vibration signal sensor, the sampling period f=50000Hz of data collector is set.

1) vibration transducer 2 and data collector 3 are arranged on the bowl mill barrel 1.

2) vibration signals collecting in the time of can calculating the bowl mill barrel and rotate a circle according to (1) formula is counted and is N=52631, vibration signal when rotating a circle by vibration transducer 2 and data collector 3 collection bowl mill barrels 1, the vibration signals collecting corresponding relation figure with the vibration signal sampled value that counts, as shown in Figure 3.

3) the interior ore milling concentration C of this bowl mill is set _w=77%, the vibration signal when record bowl mill barrel rotates a circle.Maximal value is x in the vibration signal sampled value _Max=68.44m/s ², minimum value is x _Min=-53.15m/s ², statistical packet is set counts n=100, then can calculate group according to (2) formula is Δ=1.216m/s apart from width ², the frequency that vibration signal occurred in each group when statistics bowl mill barrel 1 rotated a circle is a horizontal ordinate with the vibration signal data of the barrel 1 of collection, each class frequency is the draw statistic histogram of barrel 1 vibration signal of ordinate, as shown in Figure 4.

4) according to (3) formula, the laplacian distribution that adopts zero-mean can be calculated the estimated value of statistical parameter b as the optimal estimation that the barrel vibration signal distributes by (4) formula

Corresponding laplacian distribution figure, as shown in Figure 5.

5) the interior ore milling concentration of change bowl mill is from C _w=0% (have only water and steel ball in the bowl mill, do not have ore) is to C _w=85%, the vibration signal when gathering corresponding barrel and rotating a circle, and calculate the estimated value of parameter b by (4) formula

The record sample

K=1 wherein, 2 ..., 10, amount to 10 groups of experiments.

6) the ore milling concentration computing formula that calculates in the bowl mill according to (6) formula is: Corresponding barrel vibration signal statistical parameter estimated value

With ore milling concentration C _wGraph of a relation, as shown in Figure 6.

7) gather the barrel vibration signal of ball mill by wet process under other working condition, according to the formula of determining in the step 6):

Can calculate the estimated value of corresponding ore milling concentration

The various embodiments described above only are used to illustrate the present invention, and wherein the structure of each parts, connected mode etc. all can change to some extent, and every equivalents of carrying out on the basis of technical solution of the present invention and improvement all should not got rid of outside protection scope of the present invention.

Claims (6)

1. the ore milling concentration monitoring method of a ball mill by wet process, it may further comprise the steps:

1) vibration transducer is installed on the barrel of bowl mill, vibration transducer connects a data collector by cable; Preset central processing unit, analog digital converting unit and data storage cell in the data collector;

2) sample frequency that data collector is set is f, and the ore milling concentration in the bowl mill is C _w, gather the vibration signal of bowl mill barrel by vibration transducer, and send data collector to, draw the statistic histogram of vibration signal data by data collector;

3) according to step 2) statistic histogram drawn, the best fit approximation that adopts the laplacian distribution of zero-mean to distribute as bowl mill barrel vibration signal, promptly the probability density function p (x) of vibration signal is:

Wherein, b is the vibration signal statistical parameter, and x is the vibration signal of barrel, estimates according to the maximum likelihood of laplacian distribution, obtains the estimated value of vibration signal statistical parameter b

For:

Wherein, N is a barrel when rotating a circle, the counting of the vibration signal of data collector record; X (i), i=1,2 ..., N is a barrel when rotating a circle, the sampled value of the vibration signal that the steel-ball collision barrel in the cylindrical shell produces;

4) change the interior ore milling concentration C of bowl mill _w, and write down different ore milling concentration C _wDown, the vibration signal x (i) of barrel, i=1,2 ..., N calculates estimated value according to (2) formula

The record sample

Wherein, k=1,2 ..., l is the experiment group of ore milling concentration for a change, amounts to the experiment of l group;

5) get quadratic polynomial

Wherein,

Be the ore milling concentration C in the bowl mill _wEstimated value, by Calculate gained; a ₀, a ₁, a ₂Be undetermined parameter, try to achieve undetermined parameter a ₀, a ₁, a ₂, determine (3) formula;

6) gather the barrel vibration signal x (i) in the bowl mill operational process under the different situations, i=1,2 ..., N is by the estimated value of central processing unit according to (2) formula counting statistics parameter Bring in (3) formula of determining in the step 5), calculate the estimated value of corresponding ore milling concentration

2. the ore milling concentration monitoring method of a kind of ball mill by wet process as claimed in claim 1 is characterized in that: described step 2), the method for drawing statistic histogram is:

The sample frequency that 1. data collector is set is f, according to the rotational speed omega of bowl mill _r, when calculating barrel and rotate a circle by central processing unit, the points N of the vibration signal of data collector record;

2. the ore milling concentration that is provided with in the bowl mill is C _w, when central processing unit control analog digital converting unit collection bowl mill barrel rotates a circle, the vibration signal x (i) that the steel-ball collision barrel in the ball mill barrel that vibration transducer transmits produces, i=1,2 ..., N, and be stored in the data storage cell;

3. by central processing unit the vibration signal that collects is divided into groups, it is n that packet count is set; Central processing unit is according to the maximal value x of vibration signal _MaxMinimum value x with vibration signal _MinObtain the width Delta of group distance:

The frequency that vibration signal occurs in each group when 4. adding up the bowl mill barrel and rotating a circle, the computing method of each class frequency are: with every group of vibration signal sampled value count divided by, when barrel rotates a circle, the points N of the vibration signal that data collector writes down;

5. be horizontal ordinate with the vibration signal data, each class frequency is an ordinate, draws the statistic histogram of barrel vibration signal.

3. the ore milling concentration monitoring method of a kind of ball mill by wet process as claimed in claim 2 is characterized in that: described step 1. in, the points N of the vibration signal of data collector record is:

Wherein, fix () expression round numbers; Rotational speed omega _rUnit be rpm; The unit of sample frequency f is Hz.

4. the ore milling concentration monitoring method of a kind of ball mill by wet process as claimed in claim 2 is characterized in that: described step 3. in, the group that central processing unit is obtained apart from width Delta is:

5. the ore milling concentration monitoring method of a kind of ball mill by wet process as claimed in claim 2 is characterized in that: described step 4. in, the frequency that the 1st group of vibration signal occurs is x (i) ∈ [x _Min, x _MinCounting+Δ) divided by N; The frequency that n group vibration signal occurs is x (i) ∈ [x _Max-Δ, x _Max] in count divided by N.

6. as the ore milling concentration monitoring method of a kind of ball mill by wet process of claim 1 or 2 or 3 or 4 or 5, it is characterized in that: in the described step 5), undetermined parameter a ₀, a ₁, a ₂Try to achieve, satisfy the estimated value of ore milling concentration in the bowl mill

With ore milling concentration C in the bowl mill _wDifference Q minimum, that is:

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