D9 miner
1. The nature of the two currencies is different: bitcoin is an encrypted digital currency, and Morgan is a typical MLM currency
(1) bitcoin is a consensus network, contributing to a new payment system and a fully digital currency. It is the first decentralized peer-to-peer payment network, which is controlled by its users without a central management organization or middleman (2) Morgan is a kind of typical MLM currency, they often promise high income, the information of the founding operation team is not open, and they have the background of international large companies, so they put forward a set of seemingly reasonable economic theory
extension data: the harm of
network currency: the extensive application of
1 and virtual currency is also accelerating the rampant network robbers.
(1) in December 2006, the Shenzhen Public Security Bureau announced that it had cracked the country's largest theft network virtual property case, and 11 suspect was arrested. The gang used trojan virus to illegally steal virtual property such as tens of thousands of QQ numbers and QQ coins, and sold stolen goods on the network, making a profit of more than 700000 yuan
(2) in this case, the virtual currency Q was used as the standard of conviction and sentencing, and the police's arrest of illegal elements on suspicion of theft is a special case. The reason is that Tencent has filed with the Guangdong Provincial Price Bureau, and one q is equivalent to 1 yuan
(3) online currency is used more and more widely, for example, it can be used to buy anti-virus software online, vote for super girl, and some websites even use online currency to pay the moderator
2. Outside the business system, because indivial virtual currency has become the "equivalent" of RMB, or even "online RMB", which shows the role of "network hard currency", the illegal gains of illegal gambling can be cashed into RMB, which further promotes online gambling
however, to play mining, it is recommended to buy a more efficient ant miner instead of a graphics card. The graphics card is only a general-purpose calculation, not a specific one. The ant miner has higher efficiency and lower power consumption.
although mining does not need a large capacity storage device, it is not bad to use a small capacity solid-state hard disk, and the whole mining system will run more efficiently.
the cheap small capacity is enough
it is not worth buying the expensive one
it has no direct relationship with the mining capacity
what attracts more attention is that the proponents of the concepts of "learning ledger" and "ecation blockchain" claim that they can track and record the real-time income of learners, so as to analyze and determine which knowledge, skills, courses or majors can bring more rewards to learners, so as to provide advice and guidance for later learners; Learners themselves can also use the "learning account book" to seek sponsors who are willing to invest in their learning. The principle behind this is that the "learning account book" can track and record the rewards that learners get through each ecation blockchain, so the sponsors can ask for a certain proportion of the learners' income as their return on investment, The protocol between learners and investors is managed by smart contract. Like bitcoin's technology foundation, "learning ledger" is also built on blockchain technology, which means that every ecation blockchain acquired by learners will become an eternal record of knowledge and skills that are constantly increasing and will not be deleted on the "learning ledger"< br /> MOOCS and open ecation resource movement, which are born out of technological innovation, have and will continue to reconstruct the essence, connotation and boundary of ecation in the era of sharing economy, reshape the mission, function and organization mode of ecational institutions in the digital era, and promote the reform of teaching philosophy, content and mode in the teaching environment of technology empowerment. The development and application of blockchain technology has created a new technical basis and practice mode for the reform of ecation and teaching.
Ball mill is a kind of grinding machine widely used in silicate instry. Its main features are: strong adaptability, fine grinding for most solid materials; It has the advantages of simple structure, easy operation and management, accurate control of many process parameters such as material fineness, convenient maintenance and repair, etc. in non-metallic mineral processing, intermittent ball mill with wet operation is usually used
The structure and working principle of intermittent ball mill is shown in Fig. 3-12. The cylinder body 6 is made of steel plate and welded. There is a feeding port 7 in the middle of the cylinder body for feeding and discharging. Some cylinder bodies have a manhole in the middle for repairing the inner part of the cylinder body. The inner cavity of the cylinder body is inlaid with a lining plate 14, and both sides of the cylinder body are usually welded with forged flange rings for fixing the end cover 8. The spindle head 11 is fixedly connected with the end cover and supported by the bearing seat 12 with sliding bearing or rolling bearing fixed on the frame 13. The large gear ring 5 is fixed on the end cover on one side, and the gear ring can be in the form of internal or external teeth. The motor 1 drives the big gear ring through the friction clutch 4 and the transmission gear through the recer 3 to make the cylinder rotate
Fig. 3-12 schematic diagram of intermittent ball mill
1 - motor; 2 - clutch lever; 3 - recer; 4 - friction clutch; 5 - big gear ring; 6-barrel; 7 - feeding port; 8-END cap; 9 - plug valve; 10 - discharge pipe; 11 - spindle head; 12 - bearing pedestal; 13 - frame; 14 - liner; 15 - grinding body
the working principle of intermittent ball mill is: the grinding body 15 with a certain number of ceramic balls or gravels is loaded in the cylinder, the material to be grinded and an appropriate amount of water are added from the feeding port, and the material, water and grinding body should be properly proportioned according to the process requirements. When the cylinder rotates, the grinding body adheres to the inner wall of the cylinder under the action of centrifugal force and rotates and rises together with the cylinder. When the grinding body is brought to a certain height, it is thrown out e to the action of gravity and falls at a certain speed. During the falling process of the grinding body, the materials in the cylinder are crushed e to the impact and grinding action of the grinding body. As shown in Figure 3-13. When the material is grinded to the required fineness, stop the machine for discharging. When discharging, first make the charging port of the ball mill face up, open the cover, install the discharging pipe 10 with holes, and then rotate the cylinder to make the charging port face down. At this time, open the plug valve 9 of the discharging pipe, the slurry in the cylinder can flow out automatically, and the grinding body is blocked in the cylinder. In order to speed up the outflow of slurry and make the slurry discharge more completely, compressed air can be introced at the same time to make the slurry flow out under the pressure of compressed air
Figure 3-13 function of grinding materials of ball mill × Cylinder length, such as qm2100 × In general, the ratio of barrel length to barrel diameter is < inline media object > < imageobject > < imagedata role = 3 "fileref = image / 085_ 3.jpg">(1) the rotational speed of ball mill has a great influence on its operation. If the rotational speed is appropriate, the fine grinding operation can be carried out at a higher efficiency. If the rotation speed is too fast, the grinding body will cling to the inner wall of the cylinder and will not fall along the parabolic trajectory because of the large centrifugal force, so it can not effectively crush the material, and the ball milling speed and efficiency will be greatly reced; On the contrary, if the rotation speed is too slow, the lifting height of the grinding body is insufficient. In unit time, the grinding body has less action on the material, the crushing work is also small, and the ball milling efficiency will be reced. So the appropriate speed, that is, the ball mill cylinder speed is not too fast and not too slow case of reasonable speed
when determining the rotational speed of the mill, it is generally based on the lifting condition of the grinding body in the cylinder or the maximum crushing work of the material at the position of the separation point
when the rotational speed of the ball mill cylinder reaches a certain value, the separation angle of the outermost layer of the grinding body is equal to 0, that is, the grinding body rises to the top of the cylinder and no longer falls along the parabolic trajectory. This rotational speed is called the critical rotational speed of the ball mill, expressed as n < sub > 0 < / sub >
It is composed of the outer radius r < sub > 1 < / sub > and the angle between the position of the grinding body and the heavy line α， It can write out the balance equation of self weight and centrifugal force of grinding body, eliminate the self weight of grinding body
non-metallic mineral processing machinery and equipment
when cos α＝ 1, get the critical speed
non-metallic mineral processing machinery and equipment
where D is the inner diameter of the cylinder (m)
D -- diameter of grinding body (m)
because D ≤ D, the above formula approximates to
non metallic mineral processing machinery and equipment
through theoretical analysis and calculation, when the separation angle of the grinding body is 54 ° At 44 ', the maximum landing height can be obtained
to α＝ fifty-four ° 44 ', r = R < sub > 1 < / sub > substituting (3-21), the working speed of the mill can be obtained
non-metallic mineral processing machinery and equipment
where n is the working speed of the ball mill (R / min)
D -- inner diameter of cylinder (m)
The ratio of working speed to critical speed is called the speed ratio of ball mill_ 6. JPG "> < title > < / Title >< / picdesc > < / imagedata > < / imageobject > < / inlinemediaobject >
it should be pointed out that the mill speed calculated above ignores the influence of the sliding of the grinding body and the material on the movement of the grinding body, and is derived based on the outermost grinding body layer. In fact, the working speed of the mill is related to many factors, so far there is no final conclusion. The above theoretical formula can only be used as a reference. Therefore, the speed ratio Q tends to fluctuate in a large range, and the speed ratio Q of most ball mills is between 0.75 and 0.85
(2) power most of the power required by the ball mill in operation is consumed in beneficial work, that is, lifting the grinding body to a certain height, making it eject at a certain speed, and falling according to the parabolic trajectory to crush the material; The other small part is consumed to overcome the mechanical friction resistanceaccording to the theoretical analysis and calculation, the power consumed in lifting grinding body and material is n
non-metallic mineral processing machinery and equipment
where n is power (kw)
ρ—— The volume density of grinding body (T / M < sup > 3 < / sup >)
D - inner diameter of cylinder (m)
L - cylinder length (m)
The coefficient C in the above formula is determined by the rotational speed ratio Q and the proportional coefficient K, and the value of K is related to not only the rotational speed but also the loading amount of the grinding body In practical work, the filling factor is usually used φ To express the loading amount of grinding body in ball mill. Filling coefficient
non metallic mineral processing machinery and equipment
where m is the total mass of the grinding body of the ball mill
in different Q φ The value of K can be found in table 3-9
Table 3-9 φ Under reasonable working system, generally K ≤ 0.5, so K < sup > 4 < / sup > and K < sup > 6 < / sup > are far less than 1, coefficient
non metallic mineral processing machinery and equipment
the value of coefficient C at different speed ratio can be found out from table 3-10
Table 3-10 C value under different Q value
according to formula (3-24), the power required by the ball mill is on the high side, because in fact, when the grinding body falls, there is a part of energy to be "returned" to the cylinder, but how much of this part of energy in the total energy is still uncertain. Therefore, formula (3-24) is only for reference when selecting the matching motor of ball mill, and the final determination of motor power must be based on the actual operation data. As for the power and power reserve needed to overcome the mechanical friction resistance, it is unnecessary to calculate
(3) proction capacity there are many factors that affect the proction capacity of the mill, such as material properties, feed particle size, degree of fineness to be ground, feeding uniformity, filling degree of the mill and type of grinding body. So far, there is no calculation formula that can include all these factors, and the exact data can only be determined through proction practice, The commonly used calculation formula is as follows:
non metallic mineral processing machinery and equipment
where q is the proction capacity of ball mill (T / h)
D -- effective inner diameter of ball mill cylinder (m)
V -- effective volume of ball mill cylinder (m < sup > 3 < / sup >)
n -- rotation speed of ball mill cylinder (R / min)
m -- loading capacity of grinding body (T)
k - unit power output of ball mill (T / kW · h)
In non-metallic mineral processing, ball mill is the equipment of raw material grinding process, and its operation will directly affect the normal proction of the next process, so it should be operated under the best conditions as far as possible(1) the selection of ball mill model and specification should be determined according to the scale, technical force and maintenance capacity of the plant. Generally, large mills have high operation intensity and low unit power consumption, but the equipment is bulky, difficult to install and maintain, and not flexible enough in use. Small and medium-sized mills are small in volume, light in weight, flexible in mobility, strong in adaptability, convenient in installation and maintenance, but with low operation intensity and high unit power consumption. The number of mills is determined by calculation according to the amount of materials to be processed and the proction capacity of each mill, and proper reserve should be reserved
since the ball mill itself is heavy and vibrates ring operation, it should be installed on a solid foundation, and the foundation weight can be considered as 3-5 times of the machine weight
(2) the loading and selection of the abrasives should consider not only the pollution of the materials, but also the price, source, hardness, weight, harmful components and coloring elements, and the ones with high hardness and heavy weight are better. Commonly used are ceramic balls, corunm, natural flint, etc. Pebbles (containing 98% silica and 2.6% heavy silica) are used in many factories in China × 10N/m3 The size of grinding body is recommended to be d ≤ (1 / 18 ~ 1 / 24) d, D is the size of grinding body (mm), D is the clearance diameter of mill (mm). The surface of the grinding body should be smooth without pitswhen the total assembly amount of grinding body is fixed, the smaller the body is, the more the quantity is, and the larger the surface area is, which is beneficial to grinding; The larger the body, the smaller the quantity and the greater the impact force. Therefore, the gradation of grinding body should be large and small, not uniform. It is generally believed that 50%, 10% and 40% of large, medium and small are better, and the space-time gap is the smallest (about 22%)
There are spherical, flat and short cylindrical shapes in the grinding body. For grinding, short column is better; For grinding mainly by impact, spherical is betterthe loading amount of the grinding body is too small, the milling efficiency is low, and there are too many mutual interference and collision. Fill factor φ Indicates the filling degree of the grinding body:
non metallic mineral processing machinery and equipment
Where a -- the filling area of the grinding body on the effective section of the cylinder (m < sup > 2 < / sup >)
w-weight of abrasive body (n)
R - grinding radius (m)
L - length of grinding chamber (m)
R -- abrasive body weight (n / M < sup > 2 < / sup >)
the ball mill should be operated under full load as far as possible, because the weight proportion of the grinding body is the largest, and no-load and no-load are the most important