System for recovery of fiber from paper mill effluent, including a sieve bend screen

Claim 2

In a paper mill wherein a prepared feed pulp is furnished to the paper machines, the combination which comprises a collecting system for waste derived from various sources such as chests dumping, white water waste, spillage, and flow drains, containing long fibers entrapped in substantial quantities of contaminating matter clinging to said fibers, such as miscellaneous fibrous and non-fibrous impurity solids and dirt along with shives and fines, a treatment system for the disposal of collected waste effluent, a fiber decontamination and recovery station functionally interposed between said waste collecting system and said waste disposal system, comprising a screen providing a substantially upright screen surface having a configuration of the type whereby a liquid fraction is separable from a slurry due to successive longitudinally oriented changes of direction of the slurry flowing from the upper to the lower end of the screen, said screen surface being composed of transversely extending longitudinally spaced screen elements forming between them transverse slots for the passage of said liquid fraction, and means for supplying said collected mill waste to said screen under pressure at a rate sufficient to cause the separation thereof into a pumpable overflow fraction passing from the screen surface, and delivered from the bottom end of the screen containing cleansed long re-usable fibers separated and freed from their entrapment in said contaminating matter and fines by the operation of said screen, and a screen underflow fraction passing through the screen, containing said contaminating matter along with fines in a major portion of the waste stream liquid, for disposal in said waste disposal system.

Claim 3

The apparatus according to claim 1, wherein said waste disposal treatment system comprises a continuous settling tank receiving as feed the underflow Fraction from said screen, and delivering separated liquid and sludge containing said impurities, and means for concentrating said sludge to wet cake consistency.

Claim 4

In a paper mill wherein a prepared feed pulp is furnished to the paper machine, and wherein mill waste effluent is collected for disposal from various plant sources, a fiber recovery system for said mill waste effluent containing long re-usable fibers entrapped in contaminating matter such as miscellaneous fibrous and non-fibrous impurity solids and dirt along with shives and fines, which recovery system comprises hydrocyclonic cleaning apparatus, means for pressure-feeding said mill effluent thereto, effective to cause said cleaning apparatus to deliver a cyclone underflow fraction containing a coarse fraction of the impurities separated from said mill waste effluent, and a cyclone overflow fraction containing said re-usable fibers as well as fines and the balance of the impurities, a screen providing a substantially upright screen surface having a configuration of the type whereby a liquid fraction is separable from a slurry due to successive longitudinally oriented changes of direction of the slurry flowing from the upper to the lower end of the screen, said screen surface being composed of transversely extending longitudinally spaced screen elements forming between them transverse slots for the passage of said liquid fraction, and means for feeding said cyclone overflow fraction to said screen, at a rate sufficient to cause the separation thereof into a screen overflow fraction passing from the screen surface, and delivered from the bottom end of the screen, and adapted for re-use, containing said re-usable fibers freed of contaminating matter and of fines, and deliver a screen underflow of material passing through the screen, containing said contaminating matter along with fines for disposal.

Claim 5

In a paper mill wherein a prepared feed pulp is furnished to the paper machine, and wherein mill waste effluent is collected for disposal from various plant sources, a fiber recovery system for said mill waste effluent containing long re-usable fibers entrapped in contaminating matter such as miscellaneous fibrous and non-fibrous impurity solids and dirt along with shives and fines, which recovery system comprises hydrocyclonic cleaning apparatus, means for pressure-feeding said mill effluent thereto, effective to cause said cleaning apparatus to deliver a cyclone underflow fraction containing a coarse fraction of the impurities separated from said mill waste effluent, and a cyclone overflow fraction containing said re-usable fibers as well as fines and the balance of the impurities, a screen providing a substantially upright screen surface having a configuration of the type whereby a liquid fraction is separable from a slurry due to successive longitudinally oriented changes of direction of the slurry flowing from the upper to the lower end of the screen, said screen surface being composed of transversely extending longitudinally spaced screen elements forming between them transverse slots for the passage of said liquid fraction, and means for feeding said cyclone overflow fraction to said screen, at a rate sufficient to cause the separation thereof into a screen overflow fraction passing from the screen surface, and delivered from the bottom end of the screen, and adapted for re-use, containing said re-usable fibers freed of contaminating matter and of fines, and deliver a screen underflow of material passing through the screen, containing said contaminating matter along with fines for disposal.

Claim 6

The apparatus according to claim 3 with the addition of a continuous settling tank, and means for delivering the underflow from said screen to said settling tank effective to deliver separated water and a sludge containing said impurities.

Claim 7

The apparatus according to claim 4, with the addition of means for delivering the underflow from said hydrocyclonic cleaning apparatus to said settling tank.

Claim 8

In a paper mill wherein a prepared feed pulp is furnished to the paper machine, and wherein mill waste effluent is collected for disposal from various plant sources, a fiber recovery system for said mill waste effluent containing long re-usable fibers entrapped in contaminating matter such as miscellaneous fibrous and non-fibrous impurity solids and dirt along with shives and fines, which recovery system comprises a screen providing a substantially upright screen surface having a configuration of the type whereby a liquid fraction is separable from a slurry due to successive longitudinally oriented changes of direction of the slurry flowing from the upper to the lower end of the screen, said screen surface being composed of transversely extending longitudinally spaced screen elements forming between them transverse slots for the passage of said liquid fraction, means for supplying mill effluent to said screen at a rate sufficient to cause the separation thereof into a screen overflow fraction passing from the screen surface, and delivered from the bottom end of the screen and adapted for re-use, containing said re-usable fibers freed of contaminating matter and of ines, and underflow material passing through said screen, containing said contaminating matter along with fines in a major portion of the mill stream liquid, and hydrocyclonic cleaning apparatus having means for pressure-feeding said screen overflow thereto, and means for supplying diluent water for the operation of said hydrocyclonic cleaning apparatus, said pressure-feeding means together with said diluent water effective to cause said hydrocyclonic cleaning apparatus to deliver a cyclone underflow fraction containing residual impurities not removed by the screen, and deliver a cyclone overflow fraction containing re-usable decontaminated fibers.

Claim 9

In a paper mill wherein a prepared feed pulp is furnished to the paper machine, and wherein mill waste effluent is collected for disposal from various plant sources, a fiber recovery system for said mill waste effluent containing long re-usable fibers entrapped in contaminating matter such as miscellaneous fibrous and non-fibrous impurity solids and dirt along with shives and fines, which recovery system comprises a screen providing a substantially upright screen surface having a configuration of the type whereby a liquid fraction is separable from a slurry due to successive longitudinally oriented changes of direction of the slurry flowing from the upper to the lower end of the screen, said screen surface being composed of transversely extending longitudinally spaced screen elements forming between them transverse slots for the passage of said liquid fraction, means for supplying mill effluent to said screen at a rate sufficient to cause the separation thereof into a screen overflow fraction passing from the screen surface, and delivered from the bottom end of the screen and adapted for re-use, containing said re-usable fibers freed of contaminating matter and of ines, and underflow material passing through said screen, containing said contaminating matter along with fines in a major portion of the mill stream liquid, and hydrocyclonic cleaning apparatus having means for pressure-feeding said screen overflow thereto, and means for supplying diluent water for the operation of said hydrocyclonic cleaning apparatus, said pressure-feeding means together with said diluent water effective to cause said hydrocyclonic cleaning apparatus to deliver a cyclone underflow fraction containing residual impurities not removed by the screen, and deliver a cyclone overflow fraction containing re-usable decontaminated fibers.

Claim 10

In a paper mill wherein a prepared feed pulp is furnished to the paper machine, and wherein mill waste effluent is collected for disposal from various plant sources, a fiber recovery system for said mill waste effluent containing long re-usable fibers entrapped in contaminating matter such as miscellaneous fibrous and non-fibrous impurities and dirt along with shives and fines, which recovery system comprises a continuous clarifier, feed supply means for supplying mill waste effluent to said clarifier operable to produce an overflow of supernatant liquid, and an underflow substantially containing the original mixture of fibers and mill effluent impurities, hydrocyclone means having means for pressure-feeding the clarifier underflow to said hydrocyclone means, to effect the separation of a coarse fraction of impurities as cyclone underflow for delivery to disposal, and a cyclone overflow containing said re-usable fibers as well as fines and the balance of the impurities, a screen providing a substantially upright screen surface having a configuration of the type whereby a liquid fraction is separable from a slurry due to successive longitudinally oriented changes of direction of the slurry flowing from the upper to the lower end of the screen, said screen surface being composed of transversely extending longitudinally spaced screen elements forming between them transverse slots for the passage of said liquid fraction, means for supplying said cyclone overflow to said screen at a rate sufficient to cause the separation thereof into a screen overflow fraction passing from the screen surface, and delivered from the bottom end of the screen and adapted for re-use, containing said re-usable fibers freed of contaminating matter and of fines, and a screen underflow of material passing through the screen, containing said contaminating matter along with fines for disposal, and return means for feeding at least a substantial portion of said screen underflow to said mill waste effluent supply for separation in said clarifier.

Claim 11

In a paper mill wherein a prepared feed pulp is furnished to the paper machine, and wherein mill waste effluent is collected for disposal from various plant sources, a fiber recovery system for said mill waste effluent containing long re-usable fibers entrapped in contaminating matter such as miscellaneous fibrous and non-fibrous impurities and dirt along with shives and fines, which recovery system comprises a continuous clarifier, feed supply means for supplying mill waste effluent to said clarifier operable to produce an overflow of supernatant liquid, and an underflow substantially containing the original mixture of fibers and mill effluent impurities, hydrocyclone means having means for pressure-feeding the clarifier underflow to said hydrocyclone means, to effect the separation of a coarse fraction of impurities as cyclone underflow for delivery to disposal, and a cyclone overflow containing said re-usable fibers as well as fines and the balance of the impurities, a screen providing a substantially upright screen surface having a configuration of the type whereby a liquid fraction is separable from a slurry due to successive longitudinally oriented changes of direction of the slurry flowing from the upper to the lower end of the screen, said screen surface being composed of transversely extending longitudinally spaced screen elements forming between them transverse slots for the passage of said liquid fraction, means for supplying said cyclone overflow to said screen at a rate sufficient to cause the separation thereof into a screen overflow fraction passing from the screen surface, and delivered from the bottom end of the screen and adapted for re-use, containing said re-usable fibers freed of contaminating matter and of fines, and a screen underflow of material passing through the screen, containing said contaminating matter along with fines for disposal, and return means for feeding at least a substantial portion of said screen underflow to said mill waste effluent supply for separation in said clarifier.

Claim 12

The apparatus according to claim 7 with the addition of supply means adding diluent water to said cyclone overflow.

Claim 13

In a paper mill wherein a prepared feed pulp is furnished to the paper machine, and wherein mill waste effluent is collected for disposal from various plant sources, a fiber recovery system for said mill waste effluent containing long re-usable fibers entrapped in contaminating matter such as miscellaneous fibrous and non-fibrous impurities and dirt along with shives and fines, which recovery system comprises a continuous clarifier feed supply means for supplying mill waste effluent to said clarifier operable to produce an overflow of supernatant liquid, and an underflow mixture of fibers and mill effluent impurities, a screen providing a substantially upright screen surface having a configuration of the type whereby a liquid fraction is separable from a slurry due to successive longitudinally oriented changes of direction of the slurry flowing from the upper to the lower end of the screen, said screen surface being composed of transversely extending longitudinally spaced screen elements forming between them transverse slots for the passage of said liquid fraction, means for supplying said clarifier underflow to said screen at a rate sufficient to cause the separation thereof into a screen overflow fraction passing over the screen surface and from the bottom end of the screen and adapted for re-use, containing re-usable fibers freed of contaminating matter and of fines, and a screen underflow of material passing through the screen, containing said contaminating matter along with fines for disposal, and hydrocyclone apparatus having means for pressure feeding said screen overflow to said cyclone means, effective to cause said cyclone means to deliver re-usable fibers as cyclone overflow, adapted for re-use, and separated from cyclone underflow containing impurities not removed by said screen.

Claim 14

In a paper mill wherein a prepared feed pulp is furnished to the paper machine, and wherein mill waste effluent is collected for disposal from various plant sources, a fiber recovery system for said mill waste effluent containing long re-usable fibers entrapped in contaminating matter such as miscellaneous fibrous and non-fibrous impurities and dirt along with shives and fines, which recovery system comprises a continuous clarifier feed supply means for supplying mill waste effluent to said clarifier operable to produce an overflow of supernatant liquid, and an underflow mixture of fibers and mill effluent impurities, a screen providing a substantially upright screen surface having a configuration of the type whereby a liquid fraction is separable from a slurry due to successive longitudinally oriented changes of direction of the slurry flowing from the upper to the lower end of the screen, said screen surface being composed of transversely extending longitudinally spaced screen elements forming between them transverse slots for the passage of said liquid fraction, means for supplying said clarifier underflow to said screen at a rate sufficient to cause the separation thereof into a screen overflow fraction passing over the screen surface and from the bottom end of the screen and adapted for re-use, containing re-usable fibers freed of contaminating matter and of fines, and a screen underflow of material passing through the screen, containing said contaminating matter along with fines for disposal, and hydrocyclone apparatus having means for pressure feeding said screen overflow to said cyclone means, effective to cause said cyclone means to deliver re-usable fibers as cyclone overflow, adapted for re-use, and separated from cyclone underflow containing impurities not removed by said screen.

Claim 15

The apparatus according to claim 9, with the addition of supply means for adding diluent water for the operation of said hydrocyclone apparatus, said diluent being introduced into said cyclone means together with the screen overflow being fed to said cyclone apparatus.

Claim 16

In a paper mill wherein a prepared feed pulp is furnished to the paper machine, and wherein mill waste effluent is collected for disposal from various plant sources, a fiber recovery system for mill effluent containing long re-usable fibers entrapped in contaminating matter such as miscellaneous fibrous and non-fibrous impurities and dirt along with shives and fines, which recovery system comprises a continuous clarifier, feed supply means for supplying mill effluent to said clarifier operable to produce an overflow of supernatant liquid, and an underflow substantially containing the original mixture of long fibers and mill effluent impurities, an hydrocyclone cleaner apparatus having means for pressure feeding said clarifier underflow to said cyclone cleaner apparatus, effective to cause said cleaner apparatus to deliver a cyclone underflow fraction containing a coarse fraction of the impurities separated from said mill waste effluent for disposal, and a cyclone overflow fraction containing said re-usable fibers as well as fines and the balance of the impurities, a screen providing a substantially upright screen surface having a configuration of the type whereby a liquid fraction is separable from a slurry due to successive longitudinally oriented changes of direction of the slurry flowing from the upper to the lower end of the screen, said screen surface being composed of transversely extending longitudinally spaced screen elements forming between them transverse slots for the passage of said liquid fraction, means for supplying said cyclone overflow fraction to said screen at a rate sufficient to cause the separation thereof into a screen overflow fraction passing from the screen surface, and delivered from the bottom end of the screen and adapted for re-use, containing said re-usable fibers freed of contaminating matter and of fines, and a screen underflow of material passing through the screen, containing said contaminating matter along with fines for disposal.

Claim 17

In a paper mill wherein a prepared feed pulp is furnished to the paper machine, and wherein mill waste effluent is collected for disposal from various plant sources, a fiber recovery system for mill effluent containing long re-usable fibers entrapped in contaminating matter such as miscellaneous fibrous and non-fibrous impurities and dirt along with shives and fines, which recovery system comprises a continuous clarifier, feed supply means for supplying mill effluent to said clarifier operable to produce an overflow of supernatant liquid, and an underflow substantially containing the original mixture of long fibers and mill effluent impurities, an hydrocyclone cleaner apparatus having means for pressure feeding said clarifier underflow to said cyclone cleaner apparatus, effective to cause said cleaner apparatus to deliver a cyclone underflow fraction containing a coarse fraction of the impurities separated from said mill waste effluent for disposal, and a cyclone overflow fraction containing said re-usable fibers as well as fines and the balance of the impurities, a screen providing a substantially upright screen surface having a configuration of the type whereby a liquid fraction is separable from a slurry due to successive longitudinally oriented changes of direction of the slurry flowing from the upper to the lower end of the screen, said screen surface being composed of transversely extending longitudinally spaced screen elements forming between them transverse slots for the passage of said liquid fraction, means for supplying said cyclone overflow fraction to said screen at a rate sufficient to cause the separation thereof into a screen overflow fraction passing from the screen surface, and delivered from the bottom end of the screen and adapted for re-use, containing said re-usable fibers freed of contaminating matter and of fines, and a screen underflow of material passing through the screen, containing said contaminating matter along with fines for disposal.