I have been on a quest looking for info on the early thermo research, here's a CETEM tidbit you may find interesting, it is not Eichler's work but is inclusive of it, by the way it is "Eichler and Lopez" 1983 to find it on google, this is a google translation of the portugese copy.

December/2008
CT2008-161-00 Technical Communication prepared for the Book
Rocks Industrial Minerals: Uses and Specifications
Part 2 - Industrial Rocks and Minerals: Uses and
Specifications
Chapter 9 - pp. 205-221
CHAPTER 9
Agrominerals - silicate rocks as sources
Minerals Potassium Alternatives for Agriculture
Eder de Souza Martins1
Claudinei Gouveia de Oliveira2
Álvaro Vilela de Resende3
Marcello Silvino Ferreira de Matos4
1. INTRODUCTION
The Brazilian territory consists for the most part, in acid soils
poor in nutrients such as potassium (K). To make them productive, are
used high amounts of fertilizers, which comprise about 40%
variable costs of production. There are, however, the need to seek
economic alternatives to traditional fertilizers. Brazil has imported
Most of the K fertilizer used in agriculture, especially in
form of potassium chloride (KCl). In 2007 it produced 471 thousand
tonnes of K2O, representing 11% of national demand, which reached 4.7
Mt of imports to meet consumption was 4.1 Mt, equivalent to U.S. $ 1.5
billion (Oliveira, 2008).
There are predictions that the Brazilian demand K2O grow 50% by 2015
ie, a consumption of around 7.0 Mt that year. The recent increase
international prices of fertilizers tends to aggravate the trade deficit. With
Indeed, in 2006 the average import price of potash was $ 297 / t of K2O,
while in 2007 reached U.S. $ 370 / t. In the first half of 2008, the country
imported 2.2 Mt at an average price of U.S. $ 640 / t of K2O. Even assuming
a drop in prices to $ 500 / t, we can predict that by 2015, the
trade balance will be burdened by more than $ 3 billion per year. Location
which can be exacerbated with the expected depletion of Taquari -
Brooms in Sergipe and closing of the only production unit in potassium
operated by Vale, in the middle of next decade.
1Geólogo/UnB, D.Sc. in Geology / UnB, Researcher at EMBRAPA, Embrapa Cerrados.
2Geólogo/UnB, D.Sc. in Geology / UnB, Associate Professor IG-UnB.
3Engo Agronomist / UFL, D.Sc. in Soil Science / UFL.
4Geólogo/UnB, recently graduated.
Agrominerals - silicate rocks and minerals Alternative Sources
Potassium for Agriculture
206
It is expected that a new development of the Valley, also in
Sergipe, can result in the production of 800 thousand tonnes of K2O, but there
uncertainties about the technological feasibility of the project, and also on the
use of the reserves of Nova Olinda, State of Amazonas. In any
Therefore, it is difficult to reverse in the coming years, the framework of a large dependence
outside. This scenario requires a coordinated action to check sources
Alternative K.
Results obtained in previous research indicate that rocks containing
reasonable amounts of phlogopite or biotite can be sources
K alternatives for agricultural use. Some of the rocks with potential for use
agronomic include alkaline magmatic rocks (eg, carbonatites,
kimberlite, kamafugitos, flogopititos), metasedimentary rocks cálciosilicáticas
and products of potassium metasomatism (eg: biotite schist,
phlogopite schist, biotitito, flogopitito), with widespread distribution and variable across
nationwide. Prospecting and geochemical characterization, definition
processing methods and agronomic evaluation of systematic rocks
may result in the identification of alternative sources of nutrient efficient,
especially potassium, leading to a new group of agricultural inputs.
An inter-institutional research network was established to develop
assessment activities and experiments varied, with rocks of each
geographical region, to expand the potential use and feasibility
Economic these rocks as sources of K. Peeks to the care
significant part of the demand for nutrients in conventional and
organic agricultural production in Brazil, with positive impact on the balance
trade, and contribute to greater sustainability of
production.
In this chapter, we discuss the strategy work within the national
search rocks as alternative sources of potassium and other nutrients,
addition to preliminary results obtained in experiments conducted in Casade -
greenhouse and field.
2. MINERALOGY AND GEOLOGY
Traditional sources of potassium
About 95% of world production of potassium are used in
manufacture of fertilizers, and of these, 90% are for the manufacture of KCl
Industrial Rocks and Minerals - CETEM/2008, 2nd edition 207
and 5% for the manufacture of potassium sulphate (K2SO4). Brazil imports the
potassium mainly from Canada (29%), the world's largest producer, Russia
(19%), Belarus and Germany (18% of each country) and Israel (12%)
(Oliveira, 2008).
Despite the existence of potassium in most rocks and soils, the sources
economic of this nutrient is associated with evaporite deposits
sediment in the form of chlorides and sulfates. Only two minerals of K (and silvita
carnallite) are widely used in the production of potassium fertilizers.
Deposits of these minerals (in addition to halite) formed by evaporation of water
salt in restricted basins. Israel and Jordan, for example, produce fertilizers
potassium through the evaporation of water from the Dead Sea, from which they
halite and carnallite (Roberts, 2005).
In KCl, the potassium sulfate (K2SO4), the double sulphate of potassium and
magnesium (K2SO4.MgSO4) and potassium nitrate (KNO3) are also used.
Together they are the most important sources of K for fertilizers, and the K2SO4 the
second most used (Potafos, 1996).
Because it contains 58 to 62% K2O soluble in water, potassium chloride is
more competitive economically than other fertilizers. However, due
the high chlorine content, can not be used in some cultures, such as
pineapple and smoking by undermining its commercial value. There are restrictions on the use of
fertilizer, the fact of not being accepted in organic agriculture due to high
solubility and the presence of chlorine (Costa and Campanhola, 1997; Malavolta et
al., 2002).
Potassium sulphate, has the advantages of the supply of sulfur,
addition of potassium, and the fact of being accepted in organic agriculture (though
restrictions). Displays 50 to 52% K2O and 17 to 18% of sulfur, soluble
in water (Costa and Campanhola, 1997; Malavolta et al., 2002). America
America, Chile is the leading producer of salt, found in the Salar de
Atacama, with a reserve of about 80 million tonnes (Roberts,
2005). However, due to its high price, it is used as fertilizer.
The double sulphate of potassium and magnesium with 22% K2O, 11% Mg and
22 to 23% of S, soluble in water (Malavolta et al., 2002) is usually
obtained from langbeinita (K2Mg2 (SO4) 3), which is an important mineral potassium
commercial deposits (Roberts, 2005). Potassium nitrate has 44% of
K2O and 13% N. According to Roberts (2005), Chile has perhaps the largest reserve
Agrominerals - silicate rocks and minerals Alternative Sources
Potassium for Agriculture
208
of fertilizer in the world, the Atacama Desert, where there are about 100
million tons of salt.
Potassium chloride (KCl) is the main source of K available on the market
national. The dependence on imports, and discourage the balance
Brazilian trade involves strategic issues as the need
negotiations with a select group of supplier countries for the purchase of a
essential input for agricultural production.
3. MINERALS AND ALTERNATIVE MATERIALS
The Search for Local Sources of Potassium
Potassium is the seventh most abundant chemical element in the crust
land. However, due to their characteristics (size and ionic charge),
difficult to form economic deposits. Although part of hundreds of
minerals, only silvita and carnallite are widely used to obtain
K. The use of sylvite is also common, corresponding to the ore
exploited as a source of nutrient in Brazil (Nascimento and Loureiro, 2004).
There are reserves of primary minerals with relatively high levels of
K, found in almost all regions of the country (Tavora, 1982, Birth and
Loureiro, 2004). However, most of the minerals that have K in their
structure is insoluble or poorly soluble, with some difficulty in obtaining
element, which occurs, for example, silicates. These are minerals
formed by groups of SiO4 tetrahedrons linked by cations (Nascimento and
Loureiro, 2004). According to Oliveira and Souza (2001), silicates rich in potassium, such
as feldspars, leucite and muscovite, they are not
important sources of this nutrient, as they are not soluble in water and its
structures are broken only with difficulty, by artificial means. Already
utilization of igneous rocks as a source of K is restricted to areas where
element is a byproduct of exploitation of other substances.
For decades, carrying rocks of K occurring in the territory
been studied as an option for the supply of nutrients to plants
or alternative routes to get fertilizer. Research on the use of
alternative sources of K were emphasized between the years 1970 to 1980
(Coelho, 2005). During this period, several tests were performed in house
Greenhouse and field, in order to assess the agronomic potential of
various rocks and minerals in the supply of K.
Industrial Rocks and Minerals - CETEM/2008, 2nd edition 209
Carnallite, biotite, leucite, nepheline syenite, mica schist, feldspar,
chlorite schist, muscovite and verdigris were some of the minerals and rocks evaluated
(Lopes et al. 1972; Dutra, 1980; Faquin, 1982; Eichller and Lopes, 1983 Leite,
1985). The rocks and minerals were applied pure or mixed, fresh, or
after suffering a chemical process (acidification) or heat in order
increase the reactivity and solubility of these materials. Tried to
develop fused potassium, processes for rocks
higher levels of K2O, routes hydrometallurgical extraction of nutrients
rocks, among others. Termofertilizantes derived from silicate rocks
potassic composed of minerals with low solubility, such as the verdigris
Group study area, Minas Gerais (illite-rich rock), were obtained by
transformation vitrified material with high solubility and tested
successfully as a source of potassium.
Rocks rich in potassium feldspar (mineral of low solubility)
were transformed into kalsilita (potassium silicate high solubility) by
reaction with hydrothermal solutions, behaving similarly to KCl
as a source of potassium (Faquin, 1982 Leite, 1985).
However, the results indicated that, in most cases, the
agronomic efficiency of rock depended on their origin and composition of
factors of soil, the incubation time, the chemical treatment or heat
applied and the crops used. In general, the possibility of direct use
these rocks were dropped due to low availability of K to plants.
It took chemical or thermal treatments to increase
solubility of the rocks, which proved to be uneconomical for
high cost of processing. Finally, the strategies tested not
constitute a competitive advantage over the traditional soluble fertilizer
(KCl).
Often unsatisfactory results with the use of rocks as a source
of nutrients are related to the lack of features
mineralogy of the material used. Some of the studies cited used
basalt, feldspar, muscovite and zeolites, however with very low solubility.
The mineralogy, indicator for the solubility of minerals and
ability to release K, is extremely important factor in choosing
rocks for direct application to the soil (Nascimento and Loureiro, 2004).
The alkali feldspar and feldspathoids (anhydrous silicates similar to
feldspar, but with less silica) are considered sources
Agrominerals - silicate rocks and minerals Alternative Sources
Potassium for Agriculture
210
potential of potassium for manufacture of fertilizers, both in the form of salts,
as in the form of fused or for direct application to the soil. These two
groups fall into the orthoclase, microcline and the leucite. The first two
are feldspar and leucite (from uncommon occurrence) is a Feldspathoid. The
micas, among the silicate minerals, are the great potential for
extraction of K, due to its considerable content of K2O and its abundance.
However, for use as slow-release fertilizer, applied
directly to the soil is actually committed, studies are needed on the
soil chemical properties and kinetics of migration of ions in them, as
that these characteristics vary according to the soil and the characteristics
climatic regions (Nascimento and Loureiro, 2004).
In any event, the need for resumption of research in order
to develop new products or even to seek materials which may be
applied directly to soil to supply K, besides increasing
exploitation of traditional deposits, has become a way of reducing dependence
Brazilian imports of potassium fertilizers (Kinpo, 2003; Birth
and Loureiro, 2004; Lopes, 2005).
New Alternative Sources of Potassium
Several rocks may be more effective in the supply of K, even
when applied in nature. The K-bearing minerals in these rocks are
phlogopite, biotite and / or feldspathoids, which have solubilities more
highest among the silicates. These minerals show significant release of K
in laboratory tests on soil and incubated. These rocks have shown
promising potential for use as sources of K when crushed and used
Similarly to lime (Castro et al., 2005, Resende et al., 2005).
However, there is still lack of studies of geological prospecting,
systematization and characterization of the occurrences of these alternative materials
in the national territory (Nascimento and Loureiro, 2004).
In recent years, a partnership between Embrapa Cerrados and
University of Brasilia, began studies for the identification and
characterization of some rocks in order to use them, in nature, as
K sources for agricultural use. Rocks preliminarily studied, five
possessed characteristics for potential use as sources of potassium in
agriculture: biotite schist and flogopitito, metasomatic rocks found in
tailings emerald mining areas of New Age and Belo Horizonte, Minas
General (Figures 1, 2A and 2B), and Campo Formoso, Bahia; volcanic breccia
Industrial Rocks and Minerals - CETEM/2008, 2nd edition 211
alkaline, composed of ferromagnesian minerals, feldspathoids, zeolite and glass
volcanic, coming from Rio Verde, Goiás; carbonatite composed of carbonates,
phlogopite and iron-magnesium minerals, the region of Catalão, Goiás, and
alkaline ultramafic rock composed of ferromagnesian minerals (olivine,
pyroxene), plagioclase and phlogopite, obtained in Lages, Santa
Catarina. In general, the rocks shift with concentration above 30%
biotite or phlogopite rocks were selected for study as sources
Alternative K.







Figure 1 - Biotite-phlogopite schist found as barren of emerald mining
District of New Age-Belo Horizonte, Minas Gerais. Note the growth of pumpkin
directly on the tailings and without addition of fertilizer.
Studies in house-to-vegetation using alkaline volcanic breccia,
biotite-phlogopite schist and ultramafic alkaline as sources of K for soybeans and
millet in succession showed that the application of these rocks, simply
ground, contributed significantly to the supply of potassium to
plants already in the first crop, still remaining considerable residual effect
nutrient for the crop. Moreover, the ultramafic rock
alkaline provided also Ca and Mg and reduced soil acidity (Machado et al.
2005, Resende et al., 2005).



Considering the effects of short-term (one or two crops in conditions
home-de-vegetation), these rocks have shown around at least
50% of agronomic efficiency in relation to water soluble (KCl). Therefore
Agrominerals - silicate rocks and minerals Alternative Sources
Potassium for Agriculture
212
such rocks ground could be used as sources of gradual release
nutrients, which is a desirable feature when one considers the effect
fertilizer more durable and less risk of loss, compared to
fertilizers high solubility. Castro et al. (2005) also conducted studies
home a green, with sunflower and soybean, and found that the rocks
ultramafic alkaline biotite-phlogopite schist showed comparable efficiency
to KCl.
Figure 2 - (2A) Biotite-phlogopite schist host rock of the Emerald
deposits, a New Era-Belo Horizonte, Minas Gerais. (2B) Photomicrograph of
biotite-phlogopite schist highlighting flakes phlogopite and biotite in association
with amphibole matrix meta-ultrabasic reliquie.
4. RESEARCH AND FUTURE PROSPECTS
The Research Network of silicate rocks as sources of potassium
Initial results obtained reinforce the importance of deepening the
research related to rocks with reasonable amounts of phlogopite and / or
biotite, which should be tested for use in different conditions of soil,
crops and farming systems in different regions of the country. This is justified
the fact that these rocks are abundant with wide distribution and variable
national territory.
Thus, in 2003 was organized and established a National Network
Research whose primary purpose is to develop studies that allow for
replacement of the conventional sources of K for the use of rocks
Brazil. The starting point is given by counterparts from the Ministry of
Science and Technology (Sector Funds Agribusiness and Mineral) and
Industrial Rocks and Minerals - CETEM/2008, 2nd edition 213
Embrapa, resulting in a program of technological development with the
participation of several fueling.
Currently make up the network, units of Embrapa (Embrapa Cerrados --
CPAC, Embrapa Maize and Sorghum - CNPMS, Embrapa Dairy Cattle - CNPGL,
Embrapa Gado de Corte - CNPGC, Embrapa Soja - Embrapa Soja, Embrapa Semi-Arid
- CPATSA, Embrapa Southeast Cattle - CPPSE, Embrapa Agrobiologia - CNPAB,
Embrapa Coastal Tablelands - CPATC, Embrapa Cassava and Fruits --
CNPMF, Embrapa Rice and Beans - CNPAF, Embrapa Trigo - CNPT)
University of Brasilia - UnB, Universidade Federal de São Carlos - UFSCar,
Federal University of Bahia - UFBA, and several other institutions
research (Empresa Bahian Agricultural Development S / A - EBDA, Center
Mineral Technology - CETEM, Research Company for Mineral Resources --
CPRM and the Superintendent of Geology and Mining of Goiás - SGM). A
expectation is that a model of exploitation similar to that adopted for the
limestone, that is, with several points of production around the country, could
enable the use of these rocks. Deposits of small and medium-sized
disseminated in the main areas in which to develop activities
farming, can reduce production costs of mining, transport and
distribution, prices become affordable and thus, these rocks
would be competitive with KCl (Resende et al., 2005), since all
mining operations, processing of rocks and logistics to the
farms were restricted to a maximum radius of territorial coverage,
conditioned by economic viability. Among the current goals of the Network
include:
(i) identify, catalog and characterize geochemically new
occurrences of these rocks, especially in the Mid-South
Northeast;
(ii) development of grinding technology with the aim of achieving
efficiency in the process, adequate size and
feasibility for small mining companies;
(iii) determine the potential release of K from rocks to soil and
residual effect;
(iv) determine, regionally, the agronomic efficiency of application
directly from the crushed rock as a source of K for annual crops and
perennial in soils with different chemical and physical characteristics, and
in organic and conventional systems, providing recommendations
doses and forms of use to farmers;
Agrominerals - silicate rocks and minerals Alternative Sources
Potassium for Agriculture
214
(v) to select microorganisms biossolubilização of rocks and
develop procedures involving the handling of organisms, plants
and farming systems in order to facilitate the release of K according
with the demand of crops;
(vi) evaluate the impact of the implementation of these rocks in the release of
other accompanying elements to the soil, uptake by
plants and their beneficial effects or phytotoxic;
(vii) assess the economic feasibility of using rocks as sources
K alternatives, considering the potential of replacing the power
traditional (KCl), the cost of processing and distribution of rock
space of pits (proximity to market
consumer).
Research Priorities and Perspectives
There are several factors that are associated with rocks used as sources
alternatives and potassium are the challenges of research, among others
include:
(i) the complex composition of rocks;
(ii) the location of the deposits of these rocks in relation to local
application;
(iii) the methods of mining and milling processes, which must be
low cost;
(iv) the behavior of rocks in the interaction with the environment where they are
applied (soil, plants, organisms, environment, among others).
The diameter of grinding is a factor that has been evaluated both
efficiency in the industrial processing, as the influence on
agronomic performance of the sources. Each mineral or ore has its
grindability itself, which is characterized by the probability of breakage, and
size distribution generated. Thus, the grinding step should be
well studied before the design of equipment, for the good
performance of this stage of the process depends on the efficient use and
directed energy available.
Another important aspect concerns the possibility of maximizing
K release from silicate rocks by processes biossolubilização.
In this sense, the studies conducted so far report
Industrial Rocks and Minerals - CETEM/2008, 2nd edition 215
existence of microorganisms capable of promoting the solubilization of
rocks (Ferrari et al., 2005a, Tosta et al., 2005), which opens the way for
generation of production technologies of different fertilizers. A
bioprospecting of specific functional groups and adapted to ecosystems
rain can contribute to the supply of nutrients to plants with low
economic and environmental costs and thus consolidating
competitiveness of the national agriculture. Lopes et al. (2000) and Trinidad et al.
(2001) found that mycorrhizal colonization on papaya, performed by
symbiotic fungi in roots in the soil, systematically increases the absorption of
K. In this context, research combining solubilizing microorganisms and
mycorrhizal fungi can enhance opportunities for use of rocks in
farming systems and the production of seedlings.
The determination of the agronomic efficiency and quantification of
residual effect of K and other nutrients contained in the rocks are selected
prerequisites for the correct sizing of fertilizer recommendations
the rocks, seeking the recovery and maintenance of soil fertility and
nutritional balance in the different production systems. Therefore, this type of
evaluation should be performed in various experimental conditions in
tillage systems, crop-livestock, horticulture and
forestry and also comprising the conventional methods of production and
organic.
The organic production systems are a niche market
promising, since they allow for greater value in
marketing of products, enabling the same agricultural holding
small scale. One of the basic principles of organic agriculture is
substitution of synthetic fertilizers high solubility for other inputs
including rates of nutrient release more adjusted to the demands of
cultures over time. It is desirable that these alternative inputs
should be close to the growing regions, which reduces transportation costs and
increases the sustainability of agricultural production (Neves et al., 2004). Once
that in organic systems, the application of potassium chloride is sealed off and the
potassium sulphate is accepted with restrictions, the supply of K becomes a point
critical to organic production in tropical soils. In this case, the possibility
the use of rocks as sources of K is of strategic importance, since
that the demand for nutrients could be more easily met
employing these rocks in direct application to the ground as part of management
cover crops and composting processes for production
fertilizers enriched in K.
Agrominerals - silicate rocks and minerals Alternative Sources
Potassium for Agriculture
216
Besides potassium, some rocks may provide other nutrients and
have alkalinizing effect, acting as soil conditioner
(Andrade et al., 2002, Machado et al., 2005). Given the complex nature of
mineral constituents, it is necessary to define test procedures
appropriate, which permits a satisfactory composition and
bioavailability of existing elements in the rocks, since the answers
crop may be associated not only to K from the rocks,
but the factors and combined effects, resulting from its composition.
Calcium (Ca) and magnesium (Mg) nutrients are relatively abundant
these rocks, as well as silicon (Si) considered relevant in order to
development of various cultures, increasing the tolerance of plants to
biotic and abiotic stresses (Datnoff et al., 1991, Anderson et al., 1991,
Barbosa Filho et al., 2000). The existence of micronutrients, even in
low concentrations, can contribute significantly to the care of
demand of crops, since these are required in much
small plants. Beneficial effects on soil fertility and nutrition
plants can expand the potential use of rocks as corrective or
fertilizer for different situations of soil, crop and management, adding value
the inputs derived from these rocks because of their effect or multi-nutrient
soil conditioner.
The elements contained in rocks, potentially harmful and its
dynamics in the soil / plant, need further characterization. Effect
harmful chemicals such reactions depends, basically, the
total quantity and chemical forms in which they occur in the soil. A
occurrence of heavy metals in soluble, exchangeable, occluded,
precipitated or complexed is defining the potential polluter (MacBride,
1994) and the impact on soil quality and water and toxicity to plants and other
bodies. The Agency for Environmental Protection (EPA) adopts the level
the content of toxic heavy metal that causes 50% reduction in growth
plants (King, 1996). So far, the rocks studied were not promoted
reduction in growth or appearance of visual symptoms that could be
associated with such problems. In any case, research with these
rocks should include more detailed monitoring of the dynamics and
bioavailability of heavy metals and other elements critical of the
potential contamination of agricultural products and the environment.
Industrial Rocks and Minerals - CETEM/2008, 2nd edition 217
Indispensable is the economic evaluation of the use of rocks
selected as sources of K in different production systems
agriculture. It appears that their viability in relation to traditional sources
depends on the distance from the mine to production areas. Once determined
radius of the economic viability of the use of rocks in relation to the location of
deposits, you can reduce the cost of crop production, increasing the
competitiveness and sustainability of Brazilian agribusiness.
Achieve the goals of the Research Network, the main expected result
is the replacement of part of potassium imported sources derived from rocks
national, which can mean hundreds of millions of dollars of savings in
Brazilian trade balance. Concomitant benefits for the sector
agriculture, the mining industry would be fostered with the definition of new
types of ore. In this case, the entire production chain associated would be favored
with the generation of direct and indirect jobs, distributed diffusely in
producing regions and directly benefiting the people inland. In
Moreover, it would be possible to recycle waste from mining, since
some of these rocks are environmental liabilities in stone mines
Precious (Photo 1). As part of Science and Technology, to build a network
National survey of rocks, will open the way also for
structuring of other lines of research for the development of new
agricultural inputs derived from minerals and rocks in the territory
Brazil.
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