Bulk-bag discharge methods

This invention relates to methods for discharging particulate solids, especially hazardous or toxic materials and contaminants of the atmosphere, from bulk shipping containers, such as bulk-bags, at controlled discharge rates, in an environmentally acceptable manner which eliminates exposure of the environment and personnel to contamination by the material and which allows for an essentially clinically clean environment due to emptying and transfer of the contents to process equipment.

BACKGROUND OF THE INVENTION 
The unprecedented growth of industry since World War II and the 
introduction of new products to meet consumer demand has led to the need 
and desire to ship and handle larger quantities of raw materials in bulk 
containers. The shipping and handling of particulate solids of hazardous 
or toxic materials or contaminants of the ecosphere in a safe and 
environmentally acceptable manner has become a requirement of Federal, 
State and Municipal laws and regulations. Although the laws and 
regulations have gone a long way in protecting the public and environment 
from the deleterious effects of many of the harmful and obnoxious 
materials, they have created problems, both technical and economic for 
industry in complying with them. Materials such as asbestos, powdered 
pesticides, ground-up or particulate polymers and resins, pulverized 
minerals and even bulk shipments and handling of food stuff such as flour 
and other grains all create problems of varying degree to personnel and 
the environment when being discharged from bulk shipping containers and 
when not contained from the environment. 
Many methods and techniques have been proposed and used for shipping and 
handling such materials when in particulate or powdered form. In spite of 
all the effort and money being spent to ship and handle them in a safe way 
and environmentally acceptable manner, there continues to be a need for 
improved methods and apparatus for discharging or emptying bulk-bag 
shipping containers into process equipment in a way that does not 
contaminate the environment or expose personnel to the dust and fines that 
are always present during emptying, and in a way that is essentially 
clinically clean. The bulk-bags employed as shipping containers are made 
of flexible fabric, such as woven poly-propylene, and are capable of 
holding several hundred pounds of particulate solids. A generally 
available size has a capacity of about a ton, however they come in larger 
and smaller capacities and can be manufactured to hold several tons of 
particulate dry solids. 
It is common for industry to use bulk-bag containers as an efficient means 
to ship, receive, and handle raw materials. It is cost-effective for the 
shipper, transporter, and recipient. A problem with the use of bulk-bag 
containers is the difficulty in emptying the contents of many dry 
particulate solids. During transit, many products compress and compact to 
a point such that they will not gravity-flow out of the discharge spouts 
in the bulk-bags. Methods such as reverse soil mechanics must be employed 
to break up the mass and allow it to flow again. Each material has its own 
characteristics and usually requires individual effort to overcome its 
particular problems. In addition and perhaps most important, the 
attachment of bulk-bags to process equipment involves an operator 
connecting and disconnecting the spouts at which time exposure of the 
contents of the bulk-bag takes place. This operator and environmental 
exposure is a problem inherent in the current methods used to discharge 
bulk-bags. 
OBJECTS OF THE INVENTION 
Accordingly it is an object of this invention to provide methods and 
apparatus by which the particulate contents of a bulk-bag container can be 
discharged and/or transferred to process equipment in an essentially 
clinically clean manner with no significant exposure of the contents to 
personnel or the environment. 
Another object is to allow for the control of the rate of discharge of the 
particulate materials from the bulk-bag to the process equipment receiving 
the material. 
Still another object is to provide a system which is readily adaptable to 
handle bulk-bags currently available in domestic and foreign commerce 
having various capacities and shapes and which are made of different 
materials. 
A further object is to provide methods, apparatus and systems for 
discharging and/or transferring particulate materials, which are hazardous 
or obnoxious in powdered or dust form either to personnel or the 
environment, from bulk-bags to process equipment, in an economical and 
efficient manner and on a commercial scale, which meet the Federal, State 
and Municipal laws and regulations on safety, health and protection of the 
environment.

Referring to the Figures, the bulk-bag {18} shown in FIG. 2, is readied for 
emptying in the assembly shown in FIG. 1 as follows. 
Using a lifting device such as a fork-lift {48}, the operator attaches the 
four loops {36} of the filled, sealed bulk-bag {18} to lifting forks of 
his fork-lift {48} and elevates the bulk-bag {18} to a comfortable height 
of approximately eight (8) feet. A new thermoplastic poly-envelope {8} of 
sufficient circumference and height is pulled up from the bottom of the 
bulk-bag {18} such that the envelope {8} encases, extends and is 
temporarily held in place above the top of the bulk-bag {18}. THe straps 
{44} at the bottom of the bulk-bag {18} are pushed through small holes 
{49} made in the poly-envelope. A means such as plastic tape {50} or rope 
is used to affix and seal the bottom straps {44} of the bulk-bag {18} to 
the poly-envelope {8}. A strap-holding-device {40} is then placed below 
the elevated, enveloped, bulk-bag {18} such that the strap clamps {43} are 
positioned directly below the straps. The four straps {44} are 
individually secured to the four strap clamps {43} until the 
strap-holding-device {40} is firmly attached. The resulting assembly is 
lowered into an empty drum {1} while the internal locking-lugs {32} of the 
strap-holding-device {40}, attached by a shaft {33}, and actuated by the 
external locking lug handles {34} are maintained in an "unlocked" position 
during the loading, after which the external lock-lug handles {34} turn 
the lock-lug shaft {33} to engage the lock lug slots {35} in the 
strap-holding-device, to "lock" said device in preparation for use. 
The drum {1} is of sufficient diameter to allow easy loading of the 
bulk-bags {18} and strap-holding-device {40}. At its top, the drum {1} has 
a lip-out {7} such that it provides a flat surface to engage the 
contact/compression seal {10} and also a rim {42} around which the 
slightly smaller diameter of the poly-envelope {8} can attach. Also, 
located under the lip {7} attached to the surface of the drum {1} are four 
loop guides {51} and four loop hooks {37}. These hooks {37} allow for a 
secure attachment and easy removal of the bulk-bag loops {36} when needed. 
At the bottom, the drum {1} has a lip-out {3} sufficient enough to allow 
the lower bearing assembly {53} to maintain the drum {1} in proper 
position through-out its operation. The drum legs {54} located on the 
bottom of the drum {1} properly elevate the drum {1} such that it rests 
between the upper central and the two lower lateral {53} bearings of the 
bearing assembly when in the dolly frame {2} is in the vertical position. 
The bag preparation is completed by removing the fork-lift forks {48} from 
the loops {36} and pulling the excess length of the poly-envelope {8} 
previously prepared back and over the rim {42} of the drum {1} stretching 
and hence sealing the interior of said drum {1} from the exterior of the 
bulk-bag {18}. The four loose loops {36} of the bulk-bag {18} are then 
pulled over the rim {42} of the drum, on top of the afore mentioned 
poly-envelope {8} and fed through the loop guide {51} and slipped onto the 
loop hooks {37}. Drums would normally be prepared in advance in the above 
manner. in order to have an inventory of prepared bulk-bags ready for 
emptying. 
The operation cycle of the assembly given in FIG. 1 is next given. A 
prepared drum {1} as described in connection with FIG. 2 is loaded onto 
the vertically positioned dolly frame {2}. The bottom lip {3} of the 
loaded drum {1} maintains drum position by means of bearings (not shown) 
The operator activates hydraulic cylinder {4} causing the dolly to tip on 
pivot {57}. The drum is secured to the dolly by a drum retainer {58} with 
latch {59} and with contact bearings {60} that roll against the drum {1} 
surface. The latch {59} allows for easy release and locking of said drum. 
The dolly action causes the drum to tip from vertical to horizontal. The 
operator then activates the traversing cylinder {5} causing the dolly 
frame {2} and dolly stand {6} to traverse forward until the drum top lip 
{7} with poly-envelope {8} contacts the previous poly-envelope {9} on the 
contact/compression seal {10}. [See FIG 7a-d]. The poly-envelope {9} from 
the previous cycle has remained intact and is stretched over the ring {11} 
around the contact/compression seal {10}. This maintains the continuous 
seal between the atmosphere and interior of the discharge chamber {12}. 
From the front cover {55}, the operator reaches into the glove box {13} 
with filtered exit valve {14} and pulls the previous poly-envelope {9} 
into the discharge chamber {12} area and effects a "slip-seal" exchange. 
The previous poly-envelope {9} that was in direct contact with the 
contact/compression seal {10} is removed by slipping it off the ring {11}, 
past the contact/compression seal {10} and into the discharge chamber {12} 
for disposal. The new poly seal {8} is in direct contact with the 
contact/compression seal {10}. As the previous poly envelope {9} is pulled 
into the discharge chamber {12}, it is fed into the disposal exit collar 
{15}. This collar extends outward and is adapted to tightly secure the 
disposal poly-tube {45} which is sealed at the other end. Said poly-tube 
is of sufficient length to be gathered-back and stored over the disposal 
exit collar {15}. By reaching in from the sealed end {46} of the disposal 
exit collar {15} and simultaneously reaching through the glove box {13}, 
the operator is able to transfer from one hand to the other control of the 
old poly envelope {9}. At any time henceforth, the disposal cycle may be 
completed as described later. 
With the newly attached bulk-bag {18} exposed, the operator reaches in 
through the glove box {13} and unties the tie {16} of the duffle top {17}. 
After securing the loose duffle top {17} to the fastening ring on the 
inside wall of the discharge chamber {12}, the system is ready to begin 
discharging the contents of the bulk bag {18}. 
Slow rotation of the bulk-bag {18} within the exoskeletal drum now in a 
horizontal position begins the discharging avalanche of raw material. 
Power for rotation is provided by a drive device attached to the drive 
shaft {20}, such as a hydraulic motor or gear reduced electric motor. Drum 
{1} rotation is effected by the dolly's drive shaft {20} and wheels {21} 
upon which the drum {1} rests. This rotation is transferred directly to 
the rotating discharge chamber {12} by engagement of the receiver assembly 
{22} mounted on the drum {1} and the drive pin {23} mounted on the 
discharge chamber {12}. 
The angle of respose {24, see FIG. 3-6} of a specific raw material 
determines how high that raw material rides up the side of the drum {1} 
and bulk-bag {18}. The more difficult the flow (greater angle of repose) 
the greater the potential energy imparted to the restricted raw material 
particles. Rotating beyond its angle of repose, to its angle of slide 
{52}causes the exposed surface of the raw material to avalanche down and 
forward into the discharge chamber {12} that feeds the discharge 
passageway {25}. Rotation effectively removes most of the contents. 
With reduced volume, the raw material again approaches its angle of repose 
and avalanching slows. To return to its angle of slide {52} the main frame 
{27} with drum {1} is tilted upward from horizontal about its pivot point 
{38} and effects complete discharge. The operator activates the hydraulic 
cylinder {31} that pushes against the base {56} and tilts up the main 
frame {27} pivoting about the discharge cylinder {26}. 
The raw material flows from the bulk-bag supported externally by the drum 
{1} through the discharge chamber {12} down into the discharge passageway 
{25} and through the discharge cylinder {26}. The discharge cylinder {26} 
is a cylinder around which the main frame {27} supporting the dolly 
assembly {2 and 6} pivots (tilts up and down). As raw material enters the 
discharge passageway {25} from the discharge chamber {12}, a power driven 
auger {28} rotates clock-wise (or counter-clockwise) moving the raw 
material to the right (or to the left) to the transfer chamber {29} for 
removal. The feed rate of said auger {28} is adjusted to equal or slightly 
exceed the capacity of the transfer system {30} and it provides a positive 
raw material feed to said transfer system. From the discharge cylinder 
{26}, the raw material travels into the transfer chamber {29}, which 
remains stationary, and is the interface between the outside transfer 
equipment {30}, and the discharge cylinder {26}. This particular 
implementation utilizes a helical conveyor; most industrial transfer 
devises would work equally well. 
After the bulk-bag {18} is emptied, the operator actuates the tilt cylinder 
{31} to its tilted down, horizontal position. The lock-lug {32} assemblies 
located in the bottom of the drum {1}are released by turning each release 
handle {34} attached to its shaft {33}, the operator turns the lock-lugs 
{32} to their unlock position by disengaging the slot in the 
strap-holding-device {35}. The operator moves to the side and frees the 
loops {36} at each of the four loop hooks {37}. Using the glove box {13} 
the loops {36} are pulled inside the discharge chamber {12} and fed into 
the disposal exit collar {15}. The full volume of air of the empty 
bulk-bag is allowed to filter out of the discharge chamber area. A 
filtered exit valve {14} insures a contaminate free discharge of this 
volume of air. The filter fabric that was used to make the glove is ample 
for such a task, however vacuum assistance from the optional vacuum port 
{39} could reduce the time from approximately a minute to a fraction of 
that if need. As the air leaves the discharge chamber {12}, the 
strap-holding-device {40} is advanced forward until it is secured in the 
discharge chamber {12}. The operator now moves to the side of the unit and 
stretches the poly-envelope seal {41} around the lip of the drum {7} over 
the rim {42} and back over and onto the adjacent ring {11} attached to the 
discharge chamber {12}. The diameter of this ring {11} around the 
contact/compression seal {10} attached to the discharge chamber, is the 
same as that of the drum rim {42} and the slightly smaller diameter of the 
poly-envelope {8} also causes it to maintain its pressure fit around this 
ring for the same reason. The seal has been transferred [FIG. 7d] from the 
drum {1} to the ring around the contact/compression seal attached to the 
discharge chamber ring {11}. 
The operator now activates the cylinder {5} to traverse back the entire 
drum {1} and dolly assembly {2 and 6}. The operator continues by tipping 
down the drum {1} secured to the dolly assembly {2 and 6} from horizontal 
to vertical. The drum {1} is detached and removed. 
The last step is the removal of the strap-holding-device {40} from the back 
of the discharge chamber {12} area. Access at the rear of the discharge 
chamber {12} now enables the clamps {43} on the strap-holding-device {40} 
for each of the four straps {44} to be "unbuckled" and released. The 
strap-holding-device {40} is lifted out of the back of the sealed 
discharge chamber {12} and removed. 
The bulk-bag {18} which was partially pulled out into the disposal exit 
collar {15}, is pulled most of the way out which also starts the attached 
poly-envelope {8} into the poly-tube {45} attached to the disposal exit 
collar {15}. This action actually is turning the poly-envelope 
"inside-out" (the contaminated side remains toward the discharge chamber 
{12} area. The action stops after said poly-envelope {8} has been 
partially pulled out of the disposal exit collar {12} to a point at which 
tension is placed on the poly-envelope {8} still stretched around the 
compression seal ring {11}. At this point the designation of current or 
new poly-envelope {8} changes to old or previous poly-envelope {9}. The 
discharge cycle has been completed and attachment of new prepared drum 
with contents begins another cycle. 
The next step in the operation is disposal of the bulk-bag and the 
poly-envelope in an environmentally acceptable manner. 
After the next drum of the new cycle has connected the compression seal 
with bulk-bag {18} and attached poly-envelope {9} pulled most of the way 
out into the disposal exit collar {15}, by grabbing the loops {36} of the 
bulk-bag {18} with the closed end of the poly-tube {46} and pulling 
forward, draws the bulk-bag to the end of the poly-tube. In this way the 
bags are connected as "sausages" and a new link is formed as each new bag 
is pulled into the disposal exit collar {15} with poly-tube {45}. By 
sealing the area at the link {47} between each "sausage" and cutting it in 
the middle, a non-contaminating disconnection of these disposal units is 
easily accomplished. Heating each joint and pulling it apart while warm 
provides an excellent seal. The disposal units now consisting of the 
encased poly-tube in which the bulk-bag with poly-envelope attached with 
plastic tape is isolated in a "sausage" that can be melted down to a 5-10 
lb plastic brick. This plastic brick encapsulates any remaining 
particulate matter in the emptied bulk-bag into a solid mass suitable for 
disposal at standard municipal landfills. This completes the disposal 
cycle. 
The particulate solids which are most advantageously contained from the 
environment in accordance with this invention are hazardous or toxic 
materials, such as, asbestoses, carbon blacks, clays, powdered pesticides, 
chemicals, plastics, resins among others. The methods and apparatus and 
bulk bags of this invention are also usefull in containing from the 
environment during their unloading from shipping containers other 
materials such as flours, grains and powdered foods which in and of 
themselves are not harmful, except when fines or dusting is involved in 
their unloading operations. 
The bulk bag shipping containers of this invention are made of flexible 
fabric, such as woven poly-propylene fabric with four nylon loops at the 
top for lifting and four nylon straps at the bottom corners to allow for 
the bag to be secured to the strap holding device. The bag is constructed, 
in accordance with a preferred embodiment of this invention, using a 42 
inch wide piece of fabric. Two sides of the bag are sewn together along a 
common seam, to produce a bag which when loaded holds approximately 2400 
pounds of particulate material in the dry state, and spreads to no more 
than 48 inches in diameter when loaded, and is 48 to 54 inches in height. 
This size allows for stable stacking and side by side loading in standard 
vehicles such as trucks, trailers and railroad cars. The duffle-top is 
formed by employing a separate poly-envelope liner being slipped over the 
bag or by sewing or otherwise securing, a double duffle-top to the 
perimeter of the bag at its upper part in conjunction with its emptying 
spout, leaving enough material to form both the spout and its closure and 
the polyenvelope seal. Thus, in accordance with this invention, the bulk 
bag shipping container has both the duffle-top emptying spout and the 
poly-envelope for making the seal secured together in one unit 
construction. The bulk bag may be coated with plastic or other sealant, 
especially at its seam to prevent dusting of the fines or particulate 
matter it is to contain. 
The drum employed in this invention for holding the bulk bag may be a can 
of cylindrical shape, with a bottom and lip-out at the top, to provide a 
rim on which to implement the required rotation. The main function of the 
drum is to provide a rigid exoskeleton to the flexible bulk bag being 
emptied. The drum or can may be made of any suitable material of 
construction, such as plastic or metal, as long as it is of sufficient 
strength for the desired size of the unit. Ordinary rolled carbon steel 
has been found satisfactory of about 1/4 inch thickness for a unit 
handling a loaded bulk bag of about 2400 pounds. The dimensions of the 
drum are made to accommodate the desired size of the bulk bag to be 
emptied. In order to handle a 2400 pound bag the drum required is about 48 
inches in diameter and 60 inches in height, allowing for a 6 inch false 
bottom space for the strap holding device and space of about 6 inches at 
the top. The size of the unit may vary to accommodate bags of just a few 
hundred to a few thousand pounds, depending on just what is desired. 
The drum or can rotating mechanism supports the drum and allows it to 
rotate while being driven by one of its two axles, both being parallel to 
the can. Both parallel axles are driven by a common drive shaft. An 
important function of the rotating mechanism is to allow for control of 
the different rates and number of turns on the contents of the bulk bag 
being emptied, depending on the particulate material, its angles of 
repose, and the angle of slide encountered during emptying. This may be 
accomplished by any one of a number of available mechanisms, such as 
variable speed hydraulic or electric motors hooked up to suitable control 
devices. 
The drum or can lift mechanism is attached to the drum or can containing 
the load such as the 2400 pounds of dry particulate material in the bulk 
bag described above. This mechanism moves the loaded drum from the 
vertical position to the horizontal and then the drum travels toward the 
frames vertical section until the lip contacts and compresses the seal on 
the ring assembly. Toward the end of the emptying cycle the drum rotating 
assembly tilts to a maximum of 45 degrees from vertical zero. When the 
emptying is complete the reverse action i.e. straightening, seal-release, 
travel back, move horizontal to vertical and can release is allowed for. 
Thus, the drum lift mechanism lifts the drum, turns it into horizontal 
position, makes contact with the seal and allows for drum rotation. 
The frame lift mechanism allows the entire frame, drum and drum rotation 
assembly to tilt forward to an angle of from 0 to 45 degrees and return. 
The tilting action is necessary to facilitate the final discharge of the 
last several hundred pounds of particulate dry solids from the 2400 pound 
bulk bag. In the embodiment of this invention being used to describe it in 
detail, i.e. the 2400 pound bulk bag size, the height of the frame tilt 
mechanism is less than 14 feet and its width is about 5 feet, with a total 
overall length of about 12 feet. The frame pivots about its discharge 
assembly and it is capable of stopping at any angle between 0 and 45 
degrees. The tilt control device is preferably regulated by a load cell 
comparison device which is capable of determining the discharge flow rates 
in accordance with the automated and computer controlled aspects of my 
invention. 
The frame assembly of this invention consists of the vertical frame 
component, the pivoting horizontal frame component and the frame base with 
the pivot point. At its front, the horizontal frame component has attached 
the frame tilt mechanism; at its rear, the horizontal frame component has 
attached the drum rotating and lifting mechanism. The vertical frame 
component has the cover at its front. Internally, the vertical frame 
provides support for the ring assembly. Both the vertical and horizontal 
frame components are integrally attached. All the above pivots as a unit 
about the frame base pivot point. The function of the frame is the 
interface between the drum lifting and rotating mechanisms and the front 
cover. It allows for the support and alignment of the ring assembly and 
thus the seal to which the can lip must contact. It pivots about the 
discharge shoot at the front during the tilting procedure. The frame 
tilting mechanism attaches to the frame and controls and supports the 
frame movement. The frame employed in the 2400 pound bag unit may 
satisfactorily be made from 3 inch.times.3 inch.times.0.25 carbon steel 
tubing. 
The ring assembly consists of the ring around the contact seal and the ring 
securing the duffle-top of the bag and is held in place by the frame. The 
ring is a cylinder with a seal attached to the outside on one end. It 
turns within the frame and is guided by 4 roller assemblies running in the 
channel on its outside surface. The ring rotates-with the drum, being 
driven by contact with the lip seal contact, it maintains the contact seal 
with the drum lip and allows for the polyseal to be easily transferred 
from the drum lip to the ring assembly's lip. The ring assembly functions 
to provide, on its inside surface, a shoot from the bulk bag to the 
opening in the front, i.e. the discharge shoot. The ring assembly also 
maintains the closed system while the poly-seal transfer is taking place. 
The outside surface provides a regular smooth surface that enables dust 
tight seals to be made. 
The front cover, which includes the vacuum port, the disposal exit collar, 
the glove box, and a drain tube to wash out the interior of any loose 
particulate material during maintenance, is attached to the vertical 
section of the frame component and the horizontal frame hopper which 
includes the discharge cylinder. It allows for visual inspection of the 
discharging procedure and remains dust tight. The cover has a bag 
discharge port for the waste bags. It can be removed for seal and ring 
assembly maintenance. The function of the cover is to form a dust 
enclosure, view port and allow for handling access and maintenance and air 
control on the system. 
The control system must perform all the seven actions described in 
connection with the operation of the methods and apparatus of this 
invention; namely, raising and lowering the loaded bulk bag held in the 
drum; moving the so held drum to vertical and horizontal positions; 
rotation of the drum; tilting from zero to 45 degrees; moveing the 
unloaded particulate solids to the transfer system and operating the 
transfer system. Low speed high torque hydraulic motors or electric motors 
are an ideal match for the systems requirements, and such a system lends 
itself to being automatically controled by microprocessors. 
The transfer system for moving the emptied particulate solids from the 
hopper in the front cover to the premix or process area is preferably a 
rotary helix type of device, it may be any suitable means for moving the 
dry solids such as employing vacuum or pressure type devices for movement 
of solids. It is a feature of this invention to provide for a controlled 
rate of discharge from the transfer system to the process equipment 
receiving the solids as raw material to be further processed or chemically 
reacted. 
The methods, apparatus and articles of this invention allow for the 
emptying of bulk bags containing hazardous or toxic particulate materials 
in an environmentally safe and acceptable manner automatically, with 
minimum labor and virtually no exposure of personell to the dusting and 
fines usually associated with such unloading operations. In fact the 
invention allows for computer control from a site remote and protected 
from the area of unloading operations. For example, when the system is 
employed for unloading asbestos from bulk bags into process equipment 
where it is to be used as a raw material personel do not have to stay in 
the operations area, and if they should, the area is safe and clean 
meeting all federal, state and municipal regulations for handling 
asbestos. 
Although this invention has been described using specific examples and 
preferred embodiments, I do not intend to limit the invention except as 
expressly defined in the appended claims.