Academic literature on the topic 'Sand. Ball mills'

The mochilla lay beside the migrant trail, an abandoned black daypack still heavy with goods. The Border Patrol agent carried it to the shelter of a corner of rocks, where no one could spot him while he searched it. He dug through the contents. There was a package of refried beans in gaudy plastic, a bag of instant oatmeal, fruit punch in a bottle too small to slake a serious thirst, and other convenience food. Also a half-pound or more of white grains in a punctured bag; the agent wet a finger and tasted: only sugar. Then he heard voices approaching and scrambled up the slope to hide in the brush. There were three of them: a rangy young man with a shadowy face in the lead, an older guy in a ball cap, and a pretty young woman with raven hair behind. They were Americans, not migrants or narcos. Their skin, their clothes, even their posture gave them away. They were too relaxed, too careless to be anything else. The agent stepped out from his hiding place. They slowed but did not stop. “You all out hiking?” “Yep,” said the young man with the shadowy face. “Where you from?” “Tucson,” came the clipped reply. Then the hikers, unsmiling and eyes straight ahead, passed him at a fast clip, the chill of the encounter resisting the afternoon heat, the desert absorbing the silence. The hikers had come from the direction of the Rat’s Nest, a maze of drainages half a dozen miles above the Line, and they disappeared toward Apache Pass—not the famous Apache Pass in the Chiricahua Mountains in eastern Arizona, but a lesser pass on the shoulder of Bartolo Mountain, well south of Tucson and only nine or ten miles north of Mexico. The agent knew they weren’t out for a hike. No one comes just to hike in the contorted and contested, bone-dry mountains along this stretch of the border. Everyone has a purpose. They come to smuggle or to be smuggled. They come to scurry in moonlight and to drag themselves under the blaze of the sun across dozens of miles of steep shadeless rock.

Seafloor Massive Sulfides (SMSs), which are formed by precipitates from hydrothermal fluids vented from seafloor, have been expected as one of mineral resources to be developed. The authors have proposed the concept of seafloor mineral processing for SMS mining, where valuable minerals contained in SMS ores are separated on seafloor. To apply a ball mill to the grinding unit for seafloor mineral processing, grinding experiments were carried out using a small-scale ball mill applicable to high-pressure condition. In the experiments, wet grinding and water-filled grinding of size-classified sili

Abstract An openhole multistage completion required selective fracture stimulation, flow control, and sand control in each zone. An openhole multistage completion was designed by combining a production sleeve integrated with sand screens and inflow control devices and a fracture sleeve with high open flow port. The system was designed to use a ball drop to isolate the bottom intervals while fracturing upper intervals. After fracture stimulation, the fracture seat/ball needed to be milled. The production sleeve were designed to be shifted to the open position and the fracturing sleeve to the cl