Rio Tinto Minerals – Plant 26
The most important thing to remember when mixing PUF-Seal® is to not get in a hurry or begin mixing too many bags before the first bag has had time to “set-up”. If poured too fast, the exothermic heat cracks the polyurethane foam (PUF) surface causing ruptures that resemble eggshells. The cracked PUF surface can cause the cured foam to lose its integrity and strength.
- Install a false bottom into a mine shaft at a previously determined depth. Remember to leave 2-3 feet for a protective cover of soil & rock. PUF-Seal recommends an 8-10 foot horizontal foam plug for mine adits. False bottoms/backing can be made of 2×4 lumber and covered with plywood, cardboard and even a foam panel. Its sole purpose is to temporarily retard the liquid foam while it hardens and attaches to the rock walls. Insulation batting or other pliable materials can be used to seal any cracks prior to pouring PUF-Seal®.
- Site permitting (especially in colder weather); begin by opening several boxes of PUF-Seal® and place bags in direct sunlight. Warming the bags speeds chemical reaction time. Remove outer protective bag.
- Remove the rubber tube seal from the plastic strip divider to allow chemicals on both sides of the bags to mix together.
- Mix the bag -for about 30 seconds by holding opposite corners and shaking –vigorously. Some people prefer to knead the bag on the ground atop cardboard or other protective materials. Be careful to avoid sharp surface rocks that might puncture the bags.
- A color change to cream yellow and a noticeable inflation of the bag (CO²) indicates the bag is ready to pour. Reaction time is heavily dependent upon outside temperature.
- Cut a bag corner and allow the foam to ooze into the mine cavity. Beware that the bag will rupture if allowed to expand too much before you relieve the pressure by cutting.
- Continue the pouring process, allowing sufficient time for the foam to cool and cure. The material becomes “tacky” to the touch (10-15 minutes). Plan your pour to let one side of the cavity cool while pouring the other side. With experience, one can direct the PUF into place by applying pressure (squeezing) on the bag. At no time should the poured foam cut into the rising foam layer. Avoid stacking foam.
- VERY IMPORTANT: Avoid pouring more than 18 inches per layer (lift) of foam in order to prevent excessive heat which can potentially jeopardize the plug integrity
- While it is almost impossible to avoid dropping PUF-Seal® plastic bags into a foam pour, PUF-Seal discourages the deliberate disposal of boxes, plastic and other debris into a foam plug: (1) Discarded waste can jeopardize the foam bond with the rock walls and, (2), the US EPA considers this action to be an unlicensed solid waste disposal.
- Avoid discarding non-mixed bags. In rugged terrain, like mine sites, bag tears are inevitable. However, with caution & care, the foam can still be mixed and utilized.
- PUF-Seal recommends use of proper safety equipment (PPE), protective overalls, vinyl gloves, fall protection, if warranted, and safety eyewear. At open-sir sites (mine shafts, adit portal), mine blower fans are recommended and always use of a property fitted respirator and organic cartridge. Underground, in confined spaces, supplied air should be used.
