Since 1990s, the large horizontal sand mill has been applied to the fine grinding of non-ferrous metal ores, the second and third grinding on the ore separation line and tailing grinding in foreign countries. This has played the role of energy saving, increasing production and optimizing the technological process, and has the trend of replacing ball mill and tower grinding. This paper briefly introduces the structure, characteristics and application of large horizontal grinding machine in non-ferrous metal ore grinding. The present situation of large horizontal sand mill in China, and some views on how to popularize large horizontal sand mill in China non-ferrous metal industry have also introduced.
Up to now, more than 180 sets large horizontal sand mills have been widely used in wet grinding of lead-zinc ore, platinum gold ore, gold ore, copper ore, nickel ore, manganese molybdenum ore, magnetite, etc.
Initially, horizontal sand mills were used for fine grinding (several microns) of nonferrous metals. Since 2003, horizontal sand mill has replaced ball mill and tower mill for second or third stage of coarse grinding in mineral processing industrial process (according to different types of minerals, the feeding size is 100-300 μ m, and the discharge size is 20 μ m-50 μ m).
Features of large horizontal sand mill in metallurgy industry
The horizontal sand mill has the following characteristics when grinding metal minerals and non-metallic minerals
1. High grinding strength
The energy density in the barrel of horizontal sand mill is 300kW / m3, the energy density of tower mill is 45KW / m3, and that of ball mill is only 20 kW / m3, which makes the horizontal sand mill only need a small installation site.
2.High grinding efficiency and low energy consumption
Smaller grinding beads (1 mm to several mm) can be used in horizontal sand mills. High energy density makes it possible for smaller grinding beads to crush coarse-grained ores.
Small grinding beads, more beads in the grinding barrel can produce more impact and grinding, so as to improve the grinding efficiency.
The energy consumption of horizontal sand mill is 30% to 50% lower than that of ball mill or tower mill.
3.Increase of product productivity
The horizontal sand mill uses ceramic or oxide grinding medium instead of steel ball. The material grinded out has clean and fresh surface, which is conducive to the subsequent flotation and leaching process.
The results show that the size distribution of ore particles is improved by the grinding material of horizontal sand mill, which is also conducive to the subsequent flotation and leaching. These factors lead to the increase of productivity.
4. It is beneficial to the optimization of mineral processing technology
By using horizontal sand mill to grind metal or non-metal minerals, satisfactory material fineness and particle size distribution can be obtained directly, and the auxiliary equipment such as classification equipment, pump and pipeline required by other grinding devices are omitted.
The following figure shows the change of mineral processing process before and after adopting horizontal sand mill.
The whole sand grinding machine, including energy device, gear box and grinding system, is installed horizontally, which is convenient for maintenance and repair. The use of more wear-resistant materials and easily replaceable structures and components also reduces maintenance time. The effective service time of horizontal sand mill can be up to 99%.
6. Large capacity, high power
The grinding capacity of horizontal sand mill ranges from 500 L to 50000 L, and the installed power ranges from 200 kW to 8000 kW, which makes it possible to select suitable horizontal sand mills for metal and no-metal mineral processing production of different scale.
7.Scale up function
From experimental type to large and super large horizontal sand mills, they all have the same structure. The data obtained from the experimental sand mill can be effectively enlarged to the production equipment in 1:1.
8.Low installation cost
Due to its small volume, high productivity and open circuit grinding, the horizontal sand mill is relatively easy to arrange and has low installation cost.
9. It is conducive to the realization of new mineral processing technology
Recently developed “Albion” process is a hydrometallurgical process for treating refractory and precious metal ore concentrates, i.e. high temperature oxidation leaching of fine particle concentrate under atmospheric pressure. (the complex process required by autoclave or bioleaching method is avoided). In Albion process, fine grinding of ore powder by horizontal sand mill is an essential part.
Structure and grinding process of horizontal sand mill
1.Structure of horizontal sand mill
The grinding system of sand mill is composed of 7-10 grinding discs installed on the main shaft and material grinding ball separation system. The grinding system is driven by motor through gearbox.
2.Operation process of horizontal sand mill
A certain amount of grinding medium is filled in the grinding barrel of sand mill. A relatively independent grinding space is formed between the grinding discs. Driven by the main shaft, the grinding discs form the edge linear velocity of 12-21m/s, and transmits the energy to the grinding beads. Slurry from the pump with a certain pressure into the grinding barrel, and in the impact of beads, friction under the role of fine. The separation system at the discharge will push the beads back to the grinding area, so that there is no bead accumulation in the separation area, so as to ensure that the materials meeting the fineness requirements can flow out of the sand mill smoothly.
Application Case No.1.Zinc lead ore processing
Company:Mt Isa Mine
Application: In the year 2000, adopting sand mills: the installed power is 1100kw / set, and there are 6 horizontal sand mills with 3000L.
Grinding finesses: The feed fineness is 37 μm, the discharge of lead concentrate fineness is 12μm and discharge of zinc concentrate fineness is 12μm. And 12 μm zinc concentrate is refined to be 7 μm by another stage sand mill.
Result: The productivity of lead and zinc increased by 10% and 16% respectively. Although more than 6000 kW of grinding power has been added to the production line. The cost of final product for each ton has not increased.
Application Case No.2 . Process of platinum gold ore processing
Country: South Africa
Application: Since 2003, adopting about 30 sets 10000 L horizontal sand mills to replace ball mills and tower mills for the second and third stage grinding of the main ore mineral processing production line.
Result: The use of horizontal sand mill makes production more energy-saving, flotation efficiency improved, investment cost and production cost more competitive. After using horizontal sand mill, the productivity of platinum gold is increased by about 3%.
Application Case No.3.Processing of transition zinc lead ore
Project: Mt Isa Black Star Open Cut project
Application: Zinc lead ore in open-pit mining is usually transitional type ore, which is composed of pyrite and sulfide ore. It is a low-grade ore, but its volume is huge. Due to the difficulty of mineral processing, MT isa has not been able to carry out industrial production after 80 years of efforts. By grinding the transition zinc lead ore with large horizontal sand mill, the flotation process can be carried out normally. MT isa has started mining transitional zinc / lead ore with an initial phase of 1.5 million tons per year.
Application Case No.4. Recovery and utilization of bauxite tailings
The tailings (red mud) produced by bauxite in the preparation of alumina include iron oxide, titanium dioxide and silicon oxide. Some of the red mud has been silicified with alumina. In order to extract alumina from acid aluminosilicate, if the tailings are ground more finely by large horizontal sand mill (original ball mill), alumina can be directly decomposed in the subsequent leaching process without high temperature process or special reagent.
Other application cases of sand mill
- Lundin mining cooperation, Portugal, one set 3000 L, one set 1000 L horizontal sand mill, grinding copper tailings from 30-40 microns to 8-10 microns.
- In Peru, in 2012, antapaccay mine introduced two 5000 L horizontal sand mills. The grinding machine uses 1-6 mm grinding beads and high-energy density grinding method, which makes grinding high-efficiency and energy-saving.
- Ernest Henry magnetite / copper mine, Australia, grinding magnetite from copper tailings to 40 microns, 10000 L horizontal sand mill.
- US, Teck Resources Limited, North Pole Teck red dog zinc mine, grinds from 150 microns to 60 microns, 15000 L horizontal sand mills.
- 10000L horizontal sand mill, panaust, Laos, copper / gold mine.
- Turkey efemculuru project, gold mine, 500 L horizontal sand mill.
- Canada, Endako molybdenum molybdenum mine, 1000L horizontal sand mill.
- 3000 L horizontal sand mill, vole brownfield nickel mine, Canada.
- Macraes gold mine, New Zealand, 1000 L horizontal sand mill.
- Kazakhstan, 2014, kazakhmys group, aktogay and bozshakol copper mine project, 2 sets of 10000 Lhorizontal sand mills.
- Romania certaj project, refractory gold ore, Albion process (hydrometallurgy), 10000 L horizontal sand mill
Sinonine CDS horizontal sand mill
Sinonine is a professional development and production of mineral processing equipment enterprises. After years of hard work, the volume of horizontal sand grinder produced by sinonine is from 0.5L to 3000L, the installed power is from 4.5kw to 1250KW.
Sinonine large horizontal sand mill is a kind of high efficiency mine ultra fine grinding machine which is improved and developed by our company based on the advanced technology of Isa mill. As a type ultra-fine grinding mill, it is the most widely used, most advanced and most efficient grinding equipment. The ultra fine grinding mill can grind the ore material to be 2-20um, is widely used in all kinds ores’ concentrate regrinding like gold ore, copper ore, silver ore, lead-zinc ore and other refractory metallic & nonmetallic minerals. Through ultra-fine grinding, the ore is fully dissociated, which creates good conditions for subsequent extraction, and the recovery rate of concentrate is more than 95%.